I have a 1997 Avenger ES 4L 2.0 Automatic. It overheated and a mechanic replaced the water pump, all hoses, and the timing belt. Now, the car runs rough when idling and the check engine light is on. It stalls frequently. It runs pretty good when driving and not sitting at a light. Also, it is now overheating again. I am not sure that the thermostat has been replaced. I have replaced the spark plugs and wires. The filters are all new. I am assuming that the check engine light and rough running with stalling may be due to the O2 sensors?? I am assuming that the overheating is due to a bad thermostat? The coolant jug is showing full. When I am stopped it overheats. I put the car in neutral and give it gas to about 2K RPMs and the temp goes back down to normal. I checked and both fans are running fine. Any advice would be much appreciated! Thanks.

 

*************************UPDATE******************* **
I have fixed the overheating problem by replacing the thermostat. It is actually running a lot better but it is still idling rough. The check engine light is now not coming on as often. I still think it could be the O2 sensors but have not replaced them yet. I am not sure if there is an idle adjustment that can be made? Again, any input as to what I should check for the idling and stalling problem would be helpful. Thanks!!

 

may have a bad iac motor

 

Seen this B4 in the shop. Guy had a neon sound bad @ idle[:'(] but got better with high rpm's.Did you check your vaccum lines? Also check the back pressure coming out your exhaust.

 

Check your throttle body to make sure its clean and your getting proper air to your engine?


also on your throttle body is a little valve thing that controls the idle speed... you may want to try raising that a little bit, it has a little metallic cap that has to be removed first however...I'd use a little flat head screwdriver.

 

Best way to find out if it is a sensor on the throttle body [IAC, TPS] is to change the throttle body with a known good one.