Pontiac Repair: 93 grand am gt rough idle while in gear, mass air flow sensor, mass air flow

Question
My cat converter was glowing red so I had it replaced car still ran rough. Replaced o2 and it ran better but still idles a little rough in gear and has lost a little power while driving. I'm getting no codes only thing I can see that isn't right is the temp guage it stays very low and will only rise to "normal" while idling. It is a 3.3 v6 1993yr. Could a faulty tstat cause a loss of power? Thank you for your time.

Answer
Hi Rick:

In a rare instance yes it could. If the engine is running too cool then it will run too rich and it can cause a rough idle and it can make the converter work harder and start to glow. You could also have some sort of a sensor issue that is giving the engine computer false info and make the engine run overly rich as well. these engine were noted for Mass Air Flow sensor issues most of the time you can just take the sensor out and clean it and put it back in and they run okay again. Does the car hesitate from a stop? If so then the MAF sensor could be the issue.. ideally you need a scan tool to look at the engine data and see what the fuel trim rate is while it running and in "closed" loop to see for sure what is going on. If not it's just a plain guessing game as to what's going on here.. good luck :)