[schipdaddy]

a loss of vacuum supply causes the system to switch to the failsafe which is the maximum heat to windshield. you have roughly 18 inches of vacuum at idle but not so much at throttle, especially full throttle. have you checked your vacuum storage?? the lines get old and crack sometimes. you might hook up a vacuum pump and check them. as far as the poltergiest you might be tripping a circuit breaker?