Originally Posted by
mike_s
correct. The engine idle/speed remains the same. The tach is just bouncing all over the place. Say for example I'm doing 70mph on the highway with the cruise set. The Tach will stay at the approx 3000rpm sometimes, but mostly will bounce between 0 and 3500rpm in really weird patterns.
Very weird, I know that one of the wires on the harness on the dist. cap will do that if it makes contact with something, I believe its the blue one. Check that harness and make sure it looks new, the shop just replaced it so it should be right?