I posted this under the Neon 2Gen forum, but think it better to go here. Moderator please delete other post if necessary.

I have been trying to run down a problem with a 2002 Neon AT. It idles fine, but misses, stumbles and backfires out the intake when put under load. If you ease into the throttle it isn't as evident, but I can still feel it. When pushed hard I get a cyliner 2 misfire. I have replaced the plugs, wires, and airfilter. I have replace injector o rings, and done a seafoam and injector treatment in the tank. So where do I start next? I dont know if it is fuel or spark as these can be tricky. It has only 42k miles. I am leaning toward fuel as backfireing is often time associated with lean mixtures or timing. I will be checking the fuel pressure on the rail and see if that is within specs. I am not sure about where the fuel filter is, but seems like low miles for a change. Let me know your thoughts. Thanks

 

Try cleaning the throttle body too.
Check coil pack wires/connection
may be fried or just loose
I know they put the fuel fliter on 95's
on passanger sidein front of the rear passenger tire
it was under a metal plate.pretty much under rear seat.
check here on your year might be there.Also it just may be a bad set of wires

 

I'll do a clean on the TB and see if that helps. Other items appear fine. 58 PSI on the fuel rail. So reg, pump and filter should be fine. I suspect a sensor but not sure which one. Perhaps map.