Ok, here's the skinny: for a long time now my truck has had a idle problem, it has recently gotten worse. so more reason for it to be eradicated. sometimes (doesn't always do it) on start up the rpms won't come back down and they sick in the 1100-2100 rpm range. pumping the gas 'resets' it and it either idles normal or rises and falls repeatedly until put into gear. also, when slowing down for light or traffic they will sick in roughly the same range. the only solution i have come up with when on the road is to shift into neutral and it like goes normally after that. when slowing down and i press brake, the rpms stick like i'm power braking. b4 christmas i took to a mechanic who performed a computer test which yielded zero codes, he disconnected the battery to relearn the computer, it didn't work. he sprayed some cleaner stuff into the throttle body that cleaned it out and it performed normally- til the stuff wore off. anybody know? i'm thinking i should reset idle manuelly, but i don't if that is it. sorry for the book up there, but you guys know how it is. -wb

1993 Bronco XLT 351Windsor, KN FIPK, Flowmaster
182,560k miles

 

Disconnect your IAC and see if your base idle is set too high. Truck should idle at 650 RPM with IAC disconnected (no load). If idle is too high, then adjust your base idle adjustment screw for 650 with IAC disconnected.
If you adjust your base idle screw, you will need to check your TPS baseline when you are done. After you have completed base idle adjustment (and reconnected IAC) turn engine off. Connect voltmeter between green wire of TPS and a good chassis ground. You will need to stick a pin into the green wire and attach voltmeter to the pin. Once you are all hooked up, turn your key to the "run" position (not "start") (KOEO). Voltmeter should indicate 0.8 to 1.0 Volts at shut throttle. Operate throttle through full range and check for 4.0 to 5.0 volts at WOT. Watch for smooth voltage transition with no "flat spots" while you are operating the throttle.
Hope this helps.