I'm asking for more help on this. My '90 f250, 351,5spd manual, sticks on high idle intermittently. This problem started after I took the truck in to have the length of cold idle time increased. The Ford mechanic never solved that problem however he created this one. Often (cold especially) when I shift or come to a stop, push in on the clutch, the engine idles at 1500-2000 RPM. Even after it is at norm. operating temp. it still (not as often) does this. The air bypass, throttle position, coolant temp, have all been replaced. Mechanic thinks it may be throttle shaft. Any ideas?

 

First off, I believe that you have a bad idle air valve, but before you replace it, try and clean up the valve, and the carbon that deposits inside the intake. Use a good carb cleaner and blow as much out as you can. If it is clean, then you need to replace the valve.

Dave

http://a2ztowing.homestead.com/a2ztowing.html

 

take the plastic shield off of where the throttle linkage snaps on to the throttle body. go for a drive and when your truck is warmed up and still on fast idle get out of your truck and push the throttle back manually at the throttle body. if it idles down go back home and take it off and dip it in carburator cleaner. then slightly loosen the 4 screws holding the throttle plates on their shaft. snap the throttle a couple times and retighten the screws. open the throttle and close it a couple times to see if there is a sticky spot in the movement. if there still is find another one. put it back on and then have an idle learn procedure done to it at a garage or yourself if you know how

 

Thank You! I'll try everything!