20v Throttle issues
 

The other day the throttle on my 91 90 20v started acting up. After accelerating in low gear, when I let off the gas the throttle races up to around 4-5000 rpm and continues to climb slowly but steadily to about 6500. The problem goes away after tapping the gas pedal a few times.

At first I thought the throttle was hanging up but my guess is the engine speed would be constant if that were the case. The cable moves freely and the throttle springs back closed when moving it by hand under the hood. I tried seeing if the pedal would stick with the engine off, and it doesn't.

I thought the accelerator was the only thing that could seriously rev the engine like this. The only other thing that can move the throttle this much is the cruise? Does anyone know if the potentiometer or anything else has a motor that connects to the throttle shaft? Thanks.

Waaaay too old to have a stepper motor. Check the ISV (unplug it, then remove it and clean it, I've had them stick open and cause issues).

Just an FYI

This does appear to be a mechanical issue after all. While trying to diagnose the problem, I popped the hood after the engine began to rev up and I noticed the arm on the throttle that connects to the cruise was not going back all the way after I let off the gas. So a few days ago I disconnected the rod that connects the cruise to the throttle and the throttle has been fine ever since.