welcome to the forum,
I bet it's a ground issue.
It sounds like the ignition module is not grounding properly. The module is the rectangular unit under the distributor with two screws holding it down. THose screws serve as the ground. If there is any corrosion on them where they touch the module and distributor you could get a weak connection. Pull the module and clean up the screws and mating surface. When you re-install it put some dielectric grease between the module and dist mating surfaces. THe grease is VERY important. Without it you will fry the module in no time because heat won't dissipate.
Other thing is the pick-up coil which is that round electrical thing at the bottom of the distributor (two wire plug coming from it). I don't think that's your problem though.
Check the ignition module first
Dave
Edit: how corroded are you distributor and the internals?
[This message has been edited by ditch (edited 11-11-2005).]