it's always 1800rpm or above, going down the road. sitting still, you can rev it till it hits the limiter as many times as you want, and it returns to idle as it should every time. this is why it's so frustrating to figure out why this is acting the way it is, going down the road only !
Try throwing it in neutral when this happens and see if it falls back to idle
I think what Mike is getting at here is taking the ecm and all the sensors out of the equation-couldn't this be something as simple as a collapsed motor mount hanging the throttle linkage partially open. Have you tried pulling the gas pedal up when the engine speed isn't coming down?
