Fast idle struck on

[vegas39]

Here's a couple more question that I didn't see mentioned. Have you unplugged the wire on the solenoid? What does it do? Have you tried to unplug the switch below the thermostat housing to see what happens? Do both of those while the engine's running.

With the engine hot, I unplugged the solenoid and the idle went back to normal. I also can hear the timing advance is engaged also and it smokes more when getting on it, so that is unplugged also. If I plug both back in and pull the connector off the thermal switch, the idle drops and the advance goes back to normal. All I can figure is, some antifreeze must have worked its way into the switch as it sits down below the stat housing.

 

[IDIBRONCO]

I think you've narrowed it down to the problem.