Someone who suggested a loose connection at the distributor may be right, since the distributor body rotates when the vacuum advance moves but not when the mechanical advance works. Another place to look is the little bolt through a block where the points connection passes through the distributor body. If it cracks it can short out. I would try wiggling wires while the engine is running and see if you can get it to skip. Some of those symptoms may not show up unless the engine is under load, though.
Alternately, check the ground strap between the engine and the frame. You could have a faulty ground that shifts around as you put torque on the driveline, and you complete the circuit when you floor the gas pedal and the accelerator rod hits the body or something strange like that.
Last edited by 4ontheFloor; 08/25/2008 6:13 AM.
