Just replaced O2 sensor, car is now stalling out

1988 Pontiac Grand Prix 2.8L V6. Was running fine. Check engine light comes on. Use paper clip jumper and get trouble code 44 and 45. I replaced O2 sensor and check engine light is not coming on, yet car is now stalling out when it warms up. Cold, it is fine. Warm, runs fine when not idling. Idling, car revs up and down until it stalls, unless you put it in nuetral.....

Any takers?

First, did you clear the codes after replacing the oxygen sensor? IF so, did you buy a Bosch sensor? I used to work at Advance Auto and Bosch oxygen sensors are GARBAGE. Also, check the IAC valve passage in the throttle body. If it's carboned up, it will cause a rising and falling idle.

First, did you clear the codes after replacing the oxygen sensor? IF so, did you buy a Bosch sensor? I used to work at Advance Auto and Bosch oxygen sensors are GARBAGE. Also, check the IAC valve passage in the throttle body. If it's carboned up, it will cause a rising and falling idle.


Thanks for the response. I have a carquest part. Trouble codes are cleared.

Side note- EGR valve is not moving when I rev up engine. EGR valve is brand new (replaced in summer). I am guessing I have a vacuum problem. I can also smell a fuel mixture in the air in the engine compartment when it is idling. Anyone have ideas?

Ok guys, I just cleaned the Idle Air Control (IAC) with carb cleaner as described here:

http://www.automotiveforums.com/vbulletin/showthread.php?t=338811

I installed it, ran it, and it still idles kind of funny, but it is a little better in that it only died on me once instead of 10 times, but it is still running crappy (idle almost quits when I come to a stop). I am thinking about replacing the IAC to see if that works. Should I?