its a 94 z28 a4 just replaced the opti with a new gm opti the car has 131xxx on the clock . the opti fixed one problem i had now theres another one . the car runs alright when i first start it in the morning while cold adn the warmer it gets the worse it gets . ive done the icm mod checked plug wires the o2s are new also. im running out of things to check here any one have any ideas i mean i can floor the car and its like bluhhh it just dont do anything i barely has the power to do the speed limit while its at running tempature any suggestions

 

Do you have any dead cylinders?

 

You can double check plugs/wires and also check to see if the opti was installed correctly, and was the opti harness new? Maybe the old one has corrosion on it

 

I've seen clogged cats do this. Seems like it was all the time though, not just warmed up.

 

would a bad opti cause it to miss? i have a 96 z28 with the lt1. the plugs and wires are all new. i put a new opti in it about 2 months ago. ran awesome for about an hour after opti was kinstalled and after that it car started to miss. check engine light is on so i hooked it to a scanner. cylinder 3 is about dead. more misfires than fires. and cylinder 6 has a few misfires but not many