OK let me start with the facts:
I scanned my car and here are the results:
At idle when you just start it (car is already hot) it runs fine for about 45 seconds, then all of a sudden the idle drops about 150 rpm and the MV of the O2 on the driver side drops to about 200 and hovers around there, cylinder 7 missfire starts to count up and the car idles (obviously) like crap. After about 5 seconds of this, the RPM jumps a little and it runs fine for a couple of seconds again and then the same thing. Ok when I drive it and I am decellerating I hear a bunch of little backfires (put put put).
WHAT is wrong with my car?
Ok the following are possible scenarios that could be wrong (correct me if I'm wrong):
1) I have an exhaust leak. I think I blew the header gasket on the driver side (kinda fits with the story except for the cylinder 7 thing) I am should get a new gasket tomorrow eventhough I am not looking forward to changing it.
2) Opti, this does not however explain why it runs fine for a little bit then the crap starts. But I put it in there since people always say 'It's the Opti'.
3) O2 sensor, Could it be something this simple? Doesn't the O2 sensor take a few seconds to heat up and start telling the PCM it's thing? Why the cylinder 7 thing though?
4) None of the above. (please provide your own theory)
Thanks for your help.

 

Nothing??
I even made it easy with the multiple choice.
Someone must know more than I do.

 

I have something similar, except it's my #8 cylinder, I ordered a new opti because we checked everything else (adjusted rockers, new plug wires, checked plugs, checked map sensor) and the opti and new waterpump is going in today.

 

Island out of curosity. How many miles do you have on that engine?

- Z28WAnnaB

 

Just a mere 58K Anyone else have a clue?

 

All the above You really need to find out why that cyl, is misfiring....wire,plug,opti,rings,valve problem...then go from there.