Ignition module going bad

It sounds like your getting too many volts to it. Is there anything else weird it does? I had a 79 buick that had a bad connection at the starter from the positive side of the battery. The power windows slammed up and down and the wipers went light speed. I replaced lots of coils and moduals. The corrosion at the starter was backing up the voltage. Replaced the cable and it stoped. Anyway I still think it's getting too many volts. Good luck

I agree, it sounds like you may not have clean power on your vehicle. I would start at the battery cables and check for connections and corrosion and work my way up to the altenator. Test the altenator and see what kind of voltage it is putting out. If it is putting out live more than 14 volts, your regulator my be bad on the over voltage side. 1990 you probably have the regulator inside the altenator, but check the output voltage and make sure iut is not too high.
Check all of the wiring on your ignition system and make sure you dont have any loose of corroded connections. If you have too much resistance, then it just draws more power to make the ignition run, and can be burning out your packs.
Dont let any ground go unchecked. If you have to take the ground stud loose, and clean and sand all the connections to make sure they are grounding perfectly, then do it to all of them.
Your problem is a pain, and will be a pain to fix, so just start at one side and work your way to the other and wring out every wire.