Finally gave up and took the car to the local GM garage. Computer showed nothing wrong, but after digging through TSB's they found a reference to faulty crankshaft sensors that would limit engine rpms to a max of 4800. That was the problem. Replaced the sensor and car is back to running great.

Here's what I've tried so far - I hope someone can offer a few suggestions. Replaced the pcv valve. Cleaned out the throttle body (didn't remove it - didn't look too bad - butterfly moves easily). Cleaned the MAF. Removed the air filter and tried running without it - no change in max rpms. Removed O...

rpm's max out whether it's in park,neutral, or drive during hard acceleration.

Cleaned the iac valve, MAF and PCV. No change. Tried something I hadn't done before, revving it up in neutral. Engine start to vibrate at about 4200 rpms, and maxes out at 4400 rpms with the pedal to the floor. Looks like I've been looking at the tranny and I should be checking the engine. Any ideas...

I've been searching the forum for similar problems, and have found a few issues surrounding the pressure control solenoid, but most of these involved a P0716 code. The only cel codes i've gotten where two months ago when I first bought the car and they were for engine misfire. Replaced the plugs and...

Doesn't seem to make any difference whether the car is cold or warmed up.

If you're asking does it make any difference whether or not overdrive is engaged, then the answer is no. Same problem with O/D on or off.

Not sure I follow what you mean. Only choices are "D", "2", "L".Thanks

Replaced the transmission fluid today. Didn't solve the problem. Fluid didn't look too bad or have a burnt smell to it. Any other suggestions?Thanks

Car has 140,000 miles on it. Have only had it for 2 months, so I don't know if transmission oil has ever been changed. I'll give it a try - thanks for the suggestion.

Car runs great/shifts ok when driven easy. Problem is when you floor it, or accelerate rapidly. Tranny will drop into second gear, engine starts to redline, and you get nowhere fast. Let off the gas, tranny will shift, and start to accelerate. No cel. Took it to the local garage and they could repea...