Engine misfire? I've been getting the P0301 code?

I have turn the key on and off three times and it is giving me code 1684 can you please let me know what is it, I have little cash and cannot afford to take it to a shop
Thanks

Yes the battery was disconnected because I had to change the starter

The van is not missing constantly only when you go over 100 km hr and I notice that there is steam coming from the radiator cap I change it but it still happening, the gauge is reading normal, cooling fan is working any suggestion, I kindly appreciate all you help you is giving me because of my financial situation
Once again thank you

3.3l engine is misfiring on multiple cylinders. Getting what seems like a weak spark on 1, 3, and 6. Get little white sparks only when keeping the wire really close to the spark plug. On other cylinders the spark is arcs quite strong, blue and orange in color. I have changed coil and wires, spark plug look good but reguaged and reinstalled. I can hear injectors clicking using stethoscope. There are no engine codes. Not sure what do to next.

Correction to the message posted. On 2 4 and 5, the spark is bright white and arc goes circularly when holding the wire close to the spark plug

I changed the wires and was getting the same result so I am thinking boots are ok but will double check again.

What resistance should I see on crank sensor, and are there any particular fuses I should be checking.

I have a 2001 Dodge Caravan with 4 Cylinder 2.4 Liter Motor. I have had a misfire for over 7 months. The code Im getting is P0304 Misfire Cylinder #4. I have Replaced: Coil Pack, plugs, wires, injectors, egr valve, injector wiring harness, fuel rail. Still have the misfire. I have spark in the coil, plugs and wires so I think that it is safe to rule out ignition. I checked the compression and I have 180Psi in all 4 cylinders, so I think it is safe to rule out compression or internal damage. Im thinking maybe the injectors arent getting power, maybe the harness is bad? Im gonna pick up a noid light and check the power to the injectors. Until then, does anyone have any tips or suggestions on what to try next?
My van runs extremely rough and I get bad gas mileage.

100% no cylinder misfire codes. Drove 30 miles hoping it would set some code but it didn't. It had set a large evap leak code a few months ago but the car ran fine and after resetting that code, it hasn't come back since. The misfire started couple of months after that.

When I say arcs are going circular, its not when boots are on the plug (that would be cracked boots), its when I removed the boots and held close to the spark plug to see if I was getting spark (others might hold it close to the engine block), and that's when on the 3 cylinders spark flew arcing across the engine bore around the plugs in a circular motion. On the other three cylinders the arcs are really small flying from wire to the tip of the spark plug.

Anyway checking your recommendations now

JMac101, I am interested in the final outcome of your situation with the misfire in you 2001. I have a 2000 with 115,000 miles and am having the exact problems. I am afraid it is the pcm.

There is a fuse labeld ign which is good.

If there are no figures for crankshaft resistance then how do I know if my readings are for good or bad sensor.

You had mentioned vacuum leak and I don't see any. Why would vacuum leak cause unevevn spark. I can understand erratic idling but not weak spark

Thanks. Would large evap leak code that I mentioned before might be causing this even though it hasn't come back again