I have a 97 ranger and when I first start it the idle goses up and down and would not settle down until after it warms up. I have change Idle sensor, vacum hoses, presure switch and most of the emission control system parts. I have not replace the computer yet and if anyone has had a thought to what it could be other than the computer please let me know. it is driving me crazy on figuring it out.

 

By idle sensor do you mean the IACV because that sounds like your issue. If you did replace the IACV did you try a new one or a used one? If it was a used one try a new one or cleaning it out. Also is the truck throwing any codes?

 

thank you for the reply, Yes I have replaced the IACV a month ago and vacum hose that I found had a leak. have not replace the carbon filter yet but plan to. The truck is not throwing any codes when I check the computer and fuel presure comes out to the right numbers as the manual says it should. I was thinking that it might be the computer that is bad or a bad IACV as well.