Have a 1988 crown vic, recently it started to idle very fast when letting off of gas pedal. I was in line at bank when it revved up. I put it in neutral and rpms must have increased to 3000.
When I put it in drive the rpms went back to normal. this has happened several times. It almost seems the throttle has stuck open. I have also noticed that I can let off gas at 45 miles per hour and the speed will be maintained for mile or more or until I put on brakes to turn into drive. What could be causing engine to just speed up while idling?
I would check for a vacuum leak.
i have a 86 crown vic lTD and my car did the same thing,there is cooling lines that go into the throdle body i by passed it and it has not done it since! all so could be EGR valve sticking
dandyoun has the right idea. 3000 RPM seems like a lot though. Your 302 (5.0L) is susceptible to vacuum leaks at the intake manifold too. Another thing to look at is the IAC valve and throttle body. They get a big build-up of crud over time and should be cleaned on occasion. (Another concern caused by the poor placement of the EGR)
yes i pulled my EGR off to clean, it was pretty drity carboned up
