I just did a tune-up on my '89 and have found a reoccuring issue. The rotor within the distributor seams to wear itself loose. What I mean is the rotor has a metal piece within the plastic that fits over the shaft in the distributor and over time wore itself loose. This made the rotor overly loose on the inside of the distributor. I don't know if this is a common problem but I've replaced my rotor once before because of this. It's only been around 10k miles since the last replacement and they should last longer. Pull off your distributor cap and see if something funky is going on in there. Hope this helps you get closer to the answer. As for anyone else, has someone heard or had this 'rotor issue' before?