Codes P0171 and P0133?

Hello, do you have a scan tool that can read live engine data, most likely you have a vacuum leak causing the lean mixture and it is causing the front oxygen sensor to remain in a lower voltage range. Below 0.45v is lean and above is getting into more of a rich condition. Ideally the sensor should be swinging between 0.8 and 0.2 back to 0.8v every 0.5seconds. So, an air leak may be causing the sensor to read and stay more towards the lower voltage range longer. Or the sensor is stuck low because it's worn out and that is causing both codes. So, you need to see what the voltage signal is reading. If it's stuck below 0.45v (450mv) and not moving, then the sensor is bad.
I'll put up some service info for you about the sensor.
You have very high mileage, so the sensor may need to be changed out. But scan tool live engine data will tell you a lot.
I have seen the heater circuit inside the front oxygen sensor fail and set this code in Toyotas as well. If the heater is not working the sensor will be very slow to respond.
The heater circuit is the 2 wires on the front sensor that are the same color. One is a 12volt supply and the other is a pulsed ground by the ECM (engine computer) and on these vehicles the ECM will intentionally shut down the heater control when the sensor has a problem.

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

Okay, refresh this page, I posted some additional guides in my last posting. Take a look at the B1S1 Oxygen sensor voltage when the vehicle is fully warmed up. Is it fluctuating from 0.2-0.8v?

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

They want you to replace the intake gasket for that TSB, I would check some live data first, for intake manifold leaks, I usually smoke test the intake to look for leaks. But instead of replacing parts first, see if the fault remains after the vehicle is already warmed up. Some intake leaks will disappear when the intake manifold is hot due to expansion. So, check if the B1S1 oxygen sensor voltage changes after it warms up. With a lean condition the Fuel Trims will be positive (for example +5-10%) or higher. and when you raise the RPMs to 2,500 the Fuel trims will come down below 5% range.

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

Do you have access to All Data?

Try to hold the RPMs steady at 2,500 RPMs for 20 or 30 seconds and see if the fuel trims come down, the sensor is definitely has a slow response at idle, and when you let off the gas you can see the voltage drop off completely, that's is normal, its deceleration fuel cutoff. But hold is steady a bit more. It looks like the fuel trims are going to come down, but try not to rev it, just hold steady 2500. And if the fuel trims come down, it's a vacuum leak. Record the graph again and the fuel trim numbers if you don't mind
If you can, what's the B1S2 oxygen sensor doing?

This MAF reading is low as well, that indicates air is getting into the engine at some other point. You should also get some Mass Air Flow cleaning spray from AutoZone and clean the MAF. It will help your fuel economy. I guarantee it's dirty with that high mileage.

Okay, well, there are too many variables here right now to be sure of what's going on, how bad is the cat? On these Toyotas I just pull out the front 02 and will look in through the 02 opening with a bore scope to see the condition of the cat. You can also do a back pressure test at that location. The max exhaust back pressure is 1-2 PSI and that's all.

The exhaust leak at the gasket is an issue. There are negative and positive pulses in the exhaust so that gasket needs to be replaced. And if the cat has at all started to restrict the substrate, there is going to be back pressure and combustion gases backing up skewing the 02 readings on both upstream and downstream sensors.

The MAF at idle is low, not by much but it is low. 1.8liter engine should be roughly 2g/s or a little more. The cat's state can be at different levels too, it's not broken apart yet completely plugging up the exhaust. If it was you wouldn't be able to get it up to that higher RPMs, or it would be a no start all together. But it can be on its way to melting down. Right now, it's not able to store oxygen and that's why you're seeing the fluctuating rear 02 sensor. The next phase is melt down.

You may be correct on the intake gasket but with so many issues it's difficult to say. That Long Term fuel trim didn't budge at all, but it did when you were revving the throttle forcing exhaust out, clearing some built up combustion gases out.

The positive fuel trim numbers are most likely a combination of things. A vacuum leak causes high positive fuel trim numbers at idle with the throttle plates closed. And the fuel trims will come down when you raise the rpm because manifold pressures start to increase and approach atmospheric pressures. Thats not happening here, the short term was jumping back and forth from 0 to -5%, so it was trying to bring the long term down but couldn't. Probably because there are exhaust positive and negative pulses happening. Thats what it looked like with the back-and-forth short-term trims. I would drop the front of the exhaust and take a look at the front of the cat.

And keep in mind that cylinder misfires are what cause cats to fail. So do the spark plugs too. Check the fuel pressure, make sure it's up to spec. A weak fuel pump will cause positive fuel trims due to lack of fuel pressure/volume. The fuel pumps are really easy to get to on these, they're under the back seat. The seat pulls up from its front and there is access to the pump connectors. There's also a quick disconnect in the engine compartment.

Here is some service info on the exhaust, the code P0133 flow chart, and fuel pressure spec.

Yeah, oil will destroy a cat too. Where are you located? Unfortunately burning that much oil is just going to keep ruining cats. And replacing oil rings on pistons is no easy task. The MAF is under reporting air flow, so it's not contributing to positive fuel trims. The MAF under reporting air flow is either due to a vacuum leak where air is coming in at another location, the resistors on the MAF are dirty, or the cat is not allowing exhaust out so air can't come in.
You can run a VE test using scan data. It requires a wide-open throttle run, while recording engine data. Then input the numbers and the VE calculator will tell you how well the engine is breathing.
The instructions for the test are at the top of the web page, you'll need a back road somewhere so you can do a WOT run, without getting a speeding ticket. But it's a very helpful test if you don't have a way to do a back pressure test. What kind of emissions testing do you have in your area? Because you don't want to have to keep replacing cats every year.
This is the link to the VE test below.

https://atgtraining.com/atg-volumetric-efficiency-calculator/

Volumetric Efficiency of 40% is no good. Looks like the cat has either melted down and is restricting the exhaust, or the previous owner replaced the cat, and didn't clear out any broken sections from the old cat that might be now stuck further down the exhaust. People forget to check the rest of the exhaust when a cat melts down. It usually breaks apart and the largest chunk will get stuck and restrict the exhaust, the rest can make its way down into the either the muffler or a 2nd cat if there is one.
Thats a very high RPM, I'm surprised you got it that high. But it looks like you're going to have to take some of the exhaust apart and check for restrictions. The oil problem is going to be an issue unless you replace the engine. It will just keep taking out the cats one after another. You may think about finding a used engine to put in. This has very high mileage.

Theoretical Load only hits 43.09% with those numbers input, and yeah, the test is with wot data. The cat might be melted down into a ball like chunk, which could be bouncing around inside the converters chamber. Either way, I'm not sure what you're looking to do here. You obviously know the issues. The engine is at the end of its life. You can drive it the way it is or fix it. It wont pass any emissions inspection if you have that in your state. And if you replace the cat, the oil getting into the cylinders will only ruin another cat.
Something else to be careful about is when converters start to overheat above their operating temperatures, they will start to glow red hot. I have seen this happen on the highway, with the vehicle on fire a couple of miles down the road. So, you just have to decide how much more money you want to put into the vehicle.

Because your MAF reading was 1/2 it was this test. There might be a chunk of the cat moving around in the exhaust, or there is a wiring issue to the MAF causing its readings to be skewed. If there is a voltage or ground problem to the sensor it will change its output signal.
But I would suspect a piece of melted converter is possibly moving around in the exhaust. Some caused the MAF to read only 1/2 the air flow on the previous test.