Trying to diagnose code P0300, random multiple misfires?

You can try changing out the MAF like Ken said as well. Even try unplugging it and see if it runs on a default strategy for the MAF data. Some manufacturers do that, if it just stalls out then the ECM doesn't have a default setting for the MAF. I see in the wiring diagrams there is a MAP sensor as well. So it might run with the MAF unplugged.

These readings are telling us you may have an intake valve leaking which will affect the other cylinders. Here is a guide to help run the test. Also, while the spark plugs are out check the condition and replace if needed.

https://www.2carpros.com/articles/how-to-test-engine-compression

Please go over this guide and get back to us.

That is because of the low sampling rate, but the some of the humps do look a bit higher than others. It could also be a valve that is sticking at some points or just not sealing all the way, and like Ken said it will affect all cylinders because the compression pressure is being pushed back into the intake manifold on the compression stroke, when the intake valve is actually supposed to be closed. You can do a cylinder leakage test with the piston at top dead center, then put some compressed air into the cylinder and listen for it leaking into the intake manifold, you might hear it popping into the intake as well. But the calculated load is very high for light throttle cruising. Just looking at the Calculated load, where it's near 98% and the MAF is only at roughly 15lb/m your RPM would need to be around 3,200 RPMs for that to happen. But you're only at about 50% throttle. But do the back pressure test as well since you've got the tooling coming.
It looks like you have a MAP sensor as well, you could scope that signal, and if compression pressures are being pushed into the intake manifold you would see spikes in the MAP signal, it's only a 0 to 5volt signal, but that be good to watch for valve sealing issues. The MAP should be pretty steady as the throttle opens and closes, so if you see spikes in the signal, they shouldn't be there, at idle (high manifold vacuum) you should have low MAP voltage, and wide-open throttle (where manifold vacuum is low, positive pressure is rising) is should be higher towards 5v. Since the vehicle has one though, it's worth seeing if there are any pressure spikes coming from an intake valve not sealing.

I just mentioned the MAP because you can scope that signal and use it to tell if there are positive pressure spikes due to an intake valve issue. Your coolant temperature is low the entire time during that data. What's your long term and short-term fuel trim at idle? Warmed up but close throttle. Just looking through your live data here.

Well, I was thinking more of using the MAP to see any intake pulses that should not be there. Another test you can do for valve sealing issues is a good ole vacuum gauge on the intake manifold. If it jumps around, that's a sign of a cylinder not sealing correctly. I've had this vacuum gauge chart forever; I should have thought of this to begin with. You can see on the chart that any valve issues will cause the needle to bounce all over the place. Your scope has a pretty low sampling rate, so it's inconclusive. There is a lot of noise in that signal, those downward spikes almost look like an ignition coil or wire strike. But the fuel trims look like the engine is rich at idle, with the negative numbers and then they come up closer to 0 at higher RPMs. But try the vacuum gauge on the intake manifold and see if it's steady or bounces around. The only issue is if you can duplicate the problem while testing. Checking for crankcase pressure will tell you if the rings are sealing correctly.
If you think it's a burnt exhaust valve then I would do a cylinder leak down test with compressed air into the cylinder, I have even seen a smoke machine used to determine a burnt exhaust valve.
But it seems like you're dealing with more of an intermittent problem. Since you mention its only at certain throttle position and engine load. Put a vacuum gauge on the intake manifold, somewhere you can see it from the driver's seat. And put the car in gear, and do a little brake torque, see if that causes a valve sealing issue to show itself.
And if you catch a bouncing needle at all, then do a leak down test.
And you're sure about the plugs and wires? I know you replaced the 3 coils, and the MAF so far plus injectors. So, we're down here to only a couple things here. How do the plugs look, and the plug gaps or electrode wear. Your fuel trims increased after the injector changed out because now you have injectors that are all flowing the correct amount.
Here's the entire flow chart for a P0300 code setting (pg 3-7). So you can go through that, I know you mentioned doing a back pressure test when the tools came, so check that at idle to just to cover your bases.

How negative are the fuel trims at idle now? In-cylinder waveforms with a pressure transducer is a very effective testing method, although they do take a while to understand what you are seeing. I use a Pico scope for that type of testing because it has measurement rulers you can move from the first compression tower to the next 0 to 360 degrees, Ill post an example of that just to show you, but also have a small handheld 2 channel Hantek scope which has a multimeter and signal generator. I use that thing probably the most since I don't need a laptop to use it like a Pico requires. But the vacuum gauge with a bouncing needle will tell you right away if there is a cylinder sealing issue. I'm surprised there isn't a 02 sensor on bank 2, at least a front one, but you're right, looking at the wiring diagrams there is only 1 front and 1 post cat 02s. The 02 sensor 2 (rear) has a pretty steady voltage which is good, if the cat was allowing emissions gases passed it, the rear 02 would be fluctuating just about the same frequency as the front 02. So, it doesn't look like a converter issue, besides you would have a lack of power all the time if this was a restricted exhaust.

Well, the issue is that it will fail the inspection if they hook it up to the DLC and either the P0300 is set or depending on the extent of their testing machine, the I/M Readiness monitors are not passed (or are okay). It seems more like you're dealing with a fish bite misfire under load, which now is more likely to be ignition related, unless you end up seeing something more on your compression testing. If you didn't notice anything with a vacuum gauge during a brake torque which is a load on the engine. The cat is fine at 1 PSI. I'm not sure how you would simulate anything else, the only things I notice left are the old plugs and wires, and the slow switching of the front oxygen sensor, but that might be slow scan tool data. It should be switching from lean (0.2 roughly) to rich (0.8v roughly) every 300-500ms (0.5sec) so every 1 second it should be switching 0.2v-0.8v-0.2v-0.8v. Thats about the frequency the front oxygen sensor should be at. It's not going to give you that misfire you're experiencing, it can still be a valve intermittently sticking, but under higher loads like you're having, compression is going to be built up and be higher due to higher engine RPMs.
Check this video out, this guy does a really good job at explaining what an ignition misfire will feel like.
Granted the vehicle is older and has high mileage, so at that mileage of 225,000, it needed a new MAF, and we could see by the after results that the injectors were partially clogged. Thats all normal wear. I've been working on this 07 Nissan Pathfinder 4.0 with 257,000 miles on it. And once I fix one thing, it needs something else. The customer is a friend and I'm doing the labor for free, but he still doesn't fully understand when I'm explaining things to him. He made it about 3,000 miles since the last repair. He can't afford another vehicle because he and his wife are both very sick, so I'm just fixing things as we go. But everything is just plain worn out. I'm currently fixing 3 major vacuum leaks that it didn't have 3,000 miles ago, I showed him the last fuel trims compared to the current and its very obvious. But it also needs plugs I'm sure, the injectors are probably clogged up as well, I can feel the misfire at idle, it's got a bad cat on bank 1, etc.
I think the testing you're doing is really important though, it will help in the future for sure if someone can't figure something out. The negative fuel trims you're seeing at idle could very well be a slow switching 02, and as the engine RPMs increases the front 02 switching frequency will increase, bringing the fuel trims back to normal ranges, but on an older vehicle like this, +/-10% is normal. So, I would do the wires when you do the plugs as well, make sure they are gapped correctly and don't put in cheap plugs, you will end up replacing them with better ones in the long run anyway. Service info only gives a part number on the plugs, but I think ACDelco is GM OEM. Just check the gap on these, try not to adjust it if possible. I use rockauto a lot, they have really good prices. I'm also very interested to hear about anymore scope testing you do, after we get this vehicle squared away, you can leave me your email and keep in touch if you want to chat more on testing. We don't get many customers on here that use a scope at all, so it's really great that you're into that for testing, I use mine for anything I can. Sorry for the super long message here.

https://www.youtube.com/watch?v=L4bvnC7rz0c

I can across this video as well, it's a bit long but very interesting:

https://www.youtube.com/watch?v=PQtSrrRpHYI

AL514 is one of our best! Use 2CarPros anytime, we are here to help. Please tell a friend.

There is a ton of noise on that waveform, I don't know if they have included any filtering with the Hantek software, I tried it a couple of times when I got into scope use, but it was terrible, so I went straight to a Pico scope. The software is free to demo, it works once you plug in one of their scopes. All that noise you're seeing is probably from the ignition system, being that this vehicle has plug wires and not coil over plug design. An amp clamp will work much better. I do use the 650Amp clamp from Hantek and a 65amp from AESWave. I had a 65amp from Hantek, but it melted from an alternator wire that had high resistance and was super-hot. I wouldn't go so far as to say every misfire under load is always going to be ignition related, and intermittent sticking valve can be very difficult to diagnose, especially if it's coming and going with temperature. But glad you got it fixed up. I'll drop you an email so we can chat about scopes, there seems to be almost endless use for them now. But if you run into any other issues, use the site, it helps us out a lot when we get more traffic, no pun intended. But check out picotech. Com and I'll be in touch. Al