Hey Al, welcome! I don't have a 91 but wiring is kind-of up my alley. Probably the solenoid arced or burned shut, staying closed way to long, doing it's job too good. I think it's next to the battery, can't find my Haynes book, but your local AutoZone etc. should be able to help you with that or do a search here. I doubt if it's the actual column key switch, but it's possible. Also, maybe the starter is actually still good but just overheated, don't know if it has a thermal switch inside to shut it down. Just be careful because all this stuff runs hot power right from the battery so keep the battery disc. until you're better sure what's going on.