Chevrolet Repair: Temp Gauge Fluctuations on 98 Cavalier, coolant temperature sensor, cold air intake

Question
I have a 98 chevy cavalier 2.2L (distributorless - cold air intake / header - performance muffler/cat con) and at certain RPM's, like when giving a moderate amount of gas to get out on the highway, the temp gauge will fall to the cold mark and begin bouncing back and forth, and if you persist in trying to speed up or maintain that particular RPM, the engine will begin cutting out a bit. When you let back out of the gas some, it quits. Upon suggestion from mechanically inclined friends, I replaced the coolant temperature sensor. Didn't help. I had the alternator tested, it was bad, I replaced it. Still didn't help. The check engine light is "not" on. No codes to be read, and no bad fuses to be found. Could a thermostat possibly cause this problem?  I'm at wits end. Hope you can help. (=

Answer
Hi Wesley... there are two temp sensors one on the engine and one on the rad....install a scan tool and watch the temp readings and see if thay are constant...if not change the one that is bad...also check the 02 sensor readings to see if it may be out of wack because of the bad temp....hope this helps