Thread: '05 Comp G - Sputtering at 5Krpm at WOT and slow pull offs

I can't figure this out. I took it to a shop and all they came up with was, "put seafoam in the gas tank."

This "seems" to be an intermittent problem. Both cold and warmed up.

Pulling out from a stop and the car hesitates. Add more throttle and everything feels the same. It's like the same amount of power/hesitation until about 2,000 rpm. While cruising you can feel it missing or whatever it's doing. Then, when I floor it, it pulls nice to 4500-5000rpm and then starts sputtering. In 2nd that equates to about 70mph. And with the pedal to the floor it will not accelerate any further than 70. Same goes for 1st gear. Zero acceleration past 5000 rpm. It's like a wall. The whine of the SC'er sounds like morse code. lol.

Other times, nothing. Runs fine from idle to redline.

Also, when it is in it's sputtering mood the DIC shows around 20mpg at best at 60mph. I usually see 28-30 on there at 60mph.

It's too intermittent, but I can try to see if it's the MAF. I did new plugs a few months ago. The car was running rough then, and new plugs smoothed it right out. I may need wires/coil too. Car has 79,000 miles on it. And suggestions on brands for wires/coil??

Thanks for the info. I also have a P0420 code. Wonder if this misfiring from the coils/wires has screwed up my cat.