2000 Ford 500

I have a 2000 ford ranger xlt 2x4 3.0 with a five speed manual. My question is sometimes when im driving and I push in the clutch the idle speed stays pegged as if I was going 40 miles an hour. Sometimes I will be just pulling up to a light and the idle will just keep idling way above normal, then after awhile it will drop back to normal. This vehicle has 70000 miles on it, do you know what it could be?
June 6, 2007.

May be a carbon build up issue. Possibly in the throttle body at the plate or carbon build up in the iac motor. No check engine light? Have codes been checked?

There is no check engine light. I have not done any checks on any codes. How would you recomend to clean the throttle body and/or iac motor?

Jun 7, 2007.