Ok, Well, for the last two days, my car has had a really bad stutter, missfire problem mostly in the mid RPM range, and mostly when it was hot.

I put in some fuel injector cleaner when I filled up, and within about 2 minutes the check engine light came on, and the car ran better than it ever has it its entire life.

After about 10 minutes of driving the check engine light went out and it IMMEDIATELY started running terribly again.

I am thinking O2 sensors... is there anything else I should consider, or any ways i could test this..... THANKS A LOT!!!!

BTW:

1997 Z28 M6
Ported Heads
Hooker Long Tube Headers
SLP CAI
CC306
Crane Gold 1.6 RR
Comp 850 Lifters
Chrome-Moly Pushrods
LT4 Extreme Duty Timing Chain
PCMforless Programming
3" True Dual exhast w/ xpipe (made by me
OBD1
LT4 KM
!EGR, !AIR, !CATS

-Chris