I am getting a missfire only after the car is being driven for about 5 minutes. But it only does it under a heavy load(cruising and the flooring it) I changed the plugs, wire, opti, and water pump while I was at it. It only does it after you have been driving it for a few minutes, because when it starts and it's cold, it runs perfect.

 

Hmm....i went through a very similar situation. Replaced freaking everything: plugs, wires, even the fuel injectors. Ended up being my distributer cap. Just a thought.

 

Sounds like a blown head gasket.
Does the car get hot, or did it get hot?
Has the pcm had a tune?
Need to get your hands on a scanner.
Sounds like you only have the problem when it goes into closed loop.

 

replaced the opti, that didn't help. Car doesn't run hot at all.

 

Maybe Opti harness.

 

Typically if its the harness to the opti, the car will throw an SES light
A low or high resolution will occur.
Does the car have a SES light?
Try replacing the fuel filter.

 

nope, the only ses light it has thrown sence it started was for the right O2, and that was replaced...no ses light has come up after that. fuel filter has been replaced too....
how about the ICM...could that cause something like this? like maybe the heat has messed it up somehow??

 

Change your ignition coil, really cheap and id bet its your problem. Engine gets hot, coil gets hotter and starts to mess up. Happened to a friend of mine.

 

Mine never threw a code to trigger the light.

 

I agree that you should try the coil. I had the same problem once. Changed wires, opti, fuel filter. Still had the problem. Put a coil in and its been fine since.

Joe.

 

how much do coils cost?? anyone have a part #?? Looks pretty easy and strait forward to change out too

 

Go get it scanned instead of throwing parts at it!!!! That will tell you what it is and you can get the RIGHT part to fix it. Much cheaper....

 

Got it scanned...only things that came up were the skip shift...of course...and the right O2, and I did replace that...

 

fuel pump, when was the last time u changed/checked it? I had problems with my car running like crap after warm up and it was the fuel pump overheating after it got warmed up.