I have a montero sport 2001 v6 3.5, check engine light p301 comes on, my car putts and jerks, especially when it needs to downshift going uphill. I checked the wiring for cylinder one and it is making a spark and i changed the spark plug, took it for a test drive and it worked perfect, parked it. When i took it out for a drive a few hours later, the problem had come back, but now it is worse than ever before today i moved the wiring a bit, because when i put it back it there was a small kink in it, hoping that would solve the problem but no, it still putts and jerks just about constantly when its not in park or neutral. Any ideas on what my next step should be?? Any help will be highly appreciated!

 

Also i have p1400 coming up, i havent checked or replaced the part for that yet though, i'm not sure if they're related at all

 

Are you still getting the p301 code? Might be a good idea to double check if all the connections are reinstalled correctly. Maybe just forgot to reattach a harness? I remember forgetting to reattach a tiny hose behind the intake manifold which threw a p0400 code.

 

Try to figure out what causes the P0301 code. One way to do it is to swap ignition coil from the cylinder #1 with a known good one - say swap the left and middle coils. If your code "jumps" to a different cylinder, you know you have a bad coil. If on the other hand the code stays as P0301 then the issue is ether a bad spark plug wire, spark plug or something else dealing specifically with cylinder #1.

 

i put everything i moved back into place... i havent switched the ignition coil with a different one but i stuck a piece of metal in it, started it up and pointed the piece of metal close to another piece of metal and it sparked up so the coil works, and i replaced the spark plug with the same brand as the one i took out, put everything back together and the first test run it worked fine then when i started it back up later it was putting worse than before and the code came back

 

That is a new test This doesn't prove anything. I can make a 9v battery produce a spark, but that will not be enough juice to produce a proper spark in the cylinder. Switch two ignition coils and confirm definitively if this is electronic issue or something else.
Also, post the freeze frame data from your P0301 code.

 

freeze frame data?

 

When PCM sets an error code (Check Engine Light), it writes down some of the parameters the engine runs under at that moment - Engine temp, RPM, Speed, Fuel Trims etc. Its a snapshot of the moment the PCM decided that something is not normal. Most OBDII code readers show you the code and then you can see what the Freeze Frame data for that code is. If you understand what that data means it helps with diagnostics. Next time you read the P0301 code, don't erase it but see if you can access the FF data and post it here. It might look a little nonsensical: LTFT B1 19%, STFT B1 10%, ..... etc. That is what we are after.

 

If your sport run fine in neutral or park but jerk, puff when it's running, have you tried replacing your fuel filter?