Jeff,
There exists three funky/delicate wires on the bottom side of the
distributor, leading out of the connector and into the body. After years of
heat and vibration the insulation fails and falls off. Even careless removal
of connector can wreak havoc on them.
You might try gently feeling around while the engine is idling to reproduce
the symptoms. Conversely, you could just pull the distributor and inspect. I
encased what was left of the wires with gobs of  J.B.Weld (don't leave home
w/o it) to re-instate a secure, isolated medium around them.
Ken Lewis
http://neksiwel.20m.com/