high engine RPM

[emon]

Can some one give me a clue?
I have a 98 2.5l Ranger.
When I push the clutch in to stop or whatever, my engine raises the rpm's up for several seconds and then it decreases back down to normal idle speed.
Is this a dirty or bad sensor?

 

[Dave R]

Could very well be a dirty IAC (Idle Air Control) soleniod. It's what the computer uses to control the idle speed. It's a film canister sized fitting on the side of the throttle body, held on with two 8 m/m headed bolts. As a test pull the electrical connector and try taking the truck for a drive. Be careful though the engine may want to die due to lack of idle air. If you can drive the truck normally, except for the low idle and your high idle problems don't rear their head, then I think you've found your problem. Pull the sensor off and flush out any built up carbon and varnish with carb/TB cleaner.