At idle I still have a slight stumble. Here is what is new:

Opti
Plugs
Wires
EGR
MAF
MAP
PCV
IAC
TPS
IAT
O2's
CAT
Coil
Starter

Any ideas what else I can look at. Stumble existed b/4 everything was replaced and is still there. Acceleration is great. No hard starting. No miss at high RPM's. TB was also cleaned as well. No codes and I scanned it with Freescan and everything looked fine. Stumble got better with pcmforless tune, but it is still there.

 

anyone?

 

No ideas here. I have the same problem though. On semi-fast acceleration of the pedal (not the car) it will stumble and backfire. At all other times it is fine.

I have a few datamaster logs, showing very split blms at idle and part throttle. They max at 160 when ever it stumbles too, so this leads me to believe that it is overfueling under hard throttle tip in.

I'm going to start wiht replacing 02 sensors.

 

my car is an m6 but I have a short pause when I try to get on it coming out of first. I have clean and checked everything too. They only way I have beaten it is to dump the cluth. Describe what happens as you go along. That may help others figure out your problem. I would try a f body only place and see what they tell you.

 

fuel filter maybe? Check the fuel pressure.