First time posting on here.. hoping to get some good feedback on this issue. 2002 Monte Carlo SS 3.8. Seems like when it switches between 2nd and 3rd and SOMETIMES between 1st and 2nd that it has a BAD SPUTTER... I can let off the gas and then hit it again and its fine. But when it happens it completely bogs the car down almost like a jerking, sputtering type of feeling. Another thing since this has been going on it TERRIBLE GAS MILEAGE... I mean TERRIBLE. Things Ive done is complete tune up including fuel filter. Has anyone run into this problem. Just trying to get the car back to running smoothly again.

 

Watty:
Heres a possibility...
It could be signs of a failing fuel pump.. Check the fuel pressure at the fuel rail.. It could also be a failing MAF? (Mass Air Flow sensor)
Is the MAF an AC Delco? If it isn't... I would purchase an AC Delco MAF..and that issue should clear up..

Are you getting a CEL? (Check engine light)
If so you can go to any local auto parts and have them scan it.. its free.
If you do get any codes..let us know and we can help..
Thanks for joining the MCF Family and all things Monte Carlo!

 

No CEL on at this time. The mass airflow was replaced about a year ago.. I will check if it is AC Delco or not. Also Fuel Pump was replaced about 2 years ago.

 

Not knowing what state your from...
Maybe..you got some bad gas? I'd try some dry gas in the tank... and or some injector cleaner..

also you may wanna check and see if your catalytic converter is plugged/clogged.
Next time you drive it around...look underneath and see if its glowing red! If it is... Then youll need the catalytic converter replaced.

When you did the tune-up... are you sure the plug gap was correct?
What brand spark plugs did you use? Did you also change the wires?

 

You should still get the car scanned. Even if the CEL isn't on the PCM records intermittent faults that may cause your problems.