I have a 1995 C180 Classic that had recently developed an oscillating idle speed. It used to idle at 750 RPM but now it oscillates between 750 and 2500...just going up and down the revs. It has new plugs and an air filter. I can see no air leaks. At cold the oscillation does not occur but it begins when the egine is at normal operating temperature. Could it be the idle speed actuator? I would be very grateful for any advice.
Thanks,
John