Check the area on the right side of the engine cover (opposite from the fuel filler) to make sure the drain is completely clear. If it isn't water can collect there and play havoc with the connection to the electronic ignition box that lives there. The drain hose on my '85 had a kink in it that looked like it had been there for years, if not from the factory. Surprised it didn't cause more problems. If you need new hose you can get it at the big box home improvement stores.
Other possibilities are the usual suspects-- dist cap, rotor, and plug wires.
HTH,
///Mike