I just got my '89 4x4 22RE back up and running after a head rebuild and new fuel pump. It ran great on a trip that was about 70 miles round trip. This morning when I drove to work and then again on the way home, the idle was way high, even after warmup. The dashpot seems to be working fine... When the truck isn't running, the dashpot will depress fully on its own, or under the pressure of the throttle spring. However, when running, it doesn't go down all the way and keeps the throttle open and the idle is high. If I manually press it in, it stays put until I blip the throttle. Since the dashpot seems ok when the truck isn't running, do you think there could be a problem with the air control valve?

Strange how it worked just fine on the trip, then just started doing this the next morning...

Any thoughts? <img src="/forums/images/graemlins/confused.gif" alt="" />

Might try backing off the stop screw for the dashpot. It might be lifting too hard on the linkage and with the engine sucking in air it pulls it open. I set mine so the plunger on the DP is about 1/2 way depressed.