[Jeff Higgins]

Maybe something in the throttle linkage? What happens if you disconnect the throttle rod from the cross bar? I broke a transmission mount once, and the tranny squirming around on top of would pull the throttle open a bit.

Or, even weirder, how about the thermal time switch and the bypass solenoid? Maybe the thermal time switch is shorted internally and it sends a signal to the bypass solenoid on top of the filter console to shoot (or maybe just dribble) a priming charge. Pull the lead off the bypass solenoid and see what happens.