This is a guess as you would need the car available to fix it. I would check the distributor plate and vacuum advance for being worn out. Also take out the pick up coil in the dist and vaery carefully look at the wires to it as they used to wear out from being moved. The guage can be bad or a vacuum leaki. Again hard to diagnose over computer this one someone will need to look at.
Wednesday, November 4th, 2009 AT 12:32 PM