1997 f-250 4x4 5.8 ,eng. after starting goes into high idle and will not kick down.
after starting engine goes into high idle and will not idle most of the time.
Check the ISC unit, it could be dirty and stuck in a fixed position, also make sure your throttle body is clean, sometimes the throttle body air plate gets crud in behind it and holds the plate open too far to achieve a good idle. If all of that checks good and you still have a problem you will have to access the ECM's diagnosis to get the codes.