Problems with the throttle cable and throttle body are extremely rare. You would feel the abnormal movement in the gas pedal. I caused the same real high engine speed on my '88 Grand Caravan when I was diagnosing a cruise control problem. What I did could not happen on its own unless one of the wires going to the servo was rubbed through and grounded.
Start by watching the throttle cable under the hood while a helper works the gas pedal with the engine off. If it releases normally, watch it again when he starts the engine. If it moves on its own, unplug the vacuum hose from the cruise control servo and plug it. If that stops the high engine speed we'll have to diagnose that system.
If the engine speed is still too high look for a vacuum hose that is cracked or disconnected. There's a sticker under the hood that shows the hose routing.
Friday, June 28th, 2013 AT 9:40 PM
