My expedition has developed a rough idle too. I read a lot about the bad IAC valve, but the problem only occurs once its warmed up and in drive. If its in park, it idles smooth. The O2 sensors is a good tip though... I'll check it out.

thanks.

 

I have a 97 expd with a problem at start up and fells like a miss between 40-65mph and 1500rpm. Maybe its the same problem as stated above. Where is the iac sensor and how do you repair it?

 

Wow this has been one of the best threads Since I got my truck.
I purchased a '97 with 80k in late Oct. I now have just about 83k, and I too have been experiencing the rough idle-ing. And I thought it was the fan coming on taking horsepower from the engine.


You learrn something new everyday!!!

great thread A+++

 

Can anyone point out as to where the IAC is located on the 5.4L, and how to change it out?