I have a 97 gt it idels at 800rpms in gear. I hade a engin code that said heated o2 senser I replaced the o2 senser and removed the + battery cable to reset the computer. now when I put the car in park the cars iddle slows down and stalls. I need help

 

Which O2 sensor did your replace? My '98 has four (4) of them. The uppers are different than the lowers. I had to eventually replace all four of mine. You may need "both" uppers or both lowers. The uppers are more common to go bad. Use Ford parts. Many aftermarket manufacturers do not include the pigrtail attachment at the end of the wiring harness. You then have to splice-in the attachments from your old sensors. Not too cool of a thing to have to do. All Ford's sensors have the complete harnesses included as one piece.

Any modification on your engine will take time for the computer to readjust to. If you disconnected your battery while you did the work, you should start to smooth out after about a half tank of gas. Just run it a bit and be sure you don't need another O2 sensor or that you replaced the bad one to begin with.

 

IAC

 

IAC=IDLE AIR CONTROL (VALVE)

 

my mustang has the same problem ...especially when its cold...tonight it almost died out on me...do u think it could b the AIC?...if so how do I clean it?

 

IAC

You can use carb cleaner, but it may only solve the issue for a little bit.

 

Sounds like IAC. If the computer can't open up the IAC and feed adequate air (bypassing your throttle body) into the plenum then your car will idle like 1@#$ especially cold or running A/C etc.