Having a problem with my 1984 500 SEL idle control. I have removed the idle control valve and cleaned it solvant. I can here something shaking inside. When I cross the leads with 13 volts I can hear it click. The idle control system is putting out 12.4 volts. Sometimes more. Car idles fast sometimes with the idle control system connected but most times the car will die. I have had times when the car will run find for @ an hour. I hate to install an idle control valve and find out it is the idle control system. Is the idle control valve either open or closed, no in between?