[ssmmookkeeyy83]

well i had a 1989 chevy beretta and i put a 3.1 in it(from a 2.8) and when i test drove it i had your problem my thermosstat would either run at 218 or 150 degrees farenhiet it stuck both ways so i thought it would be smart to just take it out and the car ran at 150 (with cooling fan always on) that did not fix the problem u and i share(d) then i figured it out i must of read the haynes manual a billion times and i learned that if the temp sensor is not in the right tempature range the egr and tcc will act goofy it will turn on and off . does your car overheat/underheat. if not check for a bad temp sensor or guage the guages and sensors are knowing not to give accurate readings. hope i have been to some assistance just remember the temp sensor runs a lot of stuff and some there is not trouble codes