I tried looking at TSB's, recalls. Here is what I want you to try if the truck doesn't start again. The power distribution center that has all of the small wires coming out of it is going to be the target. I believe in a 91 it's located on the pass side inner fender under the hood. It will be a black box with what appears to be hundreds of wires going into a wiring harness.
If the truck doesn't start again, carefully cut open the harness. I believe within the first 12 to 18 inches you will find wires spliced together. If they are green and corroded, cut them apart and resolder it. Any corroded splices need to be redone. Just make sure to protect your work with a quality electrical tape. Then, retape the wiring harness where you opened it to protect the wires in it.
I recommend doing this before it lets you down again. I'm confident your problem lies there.
Please let me know if this helps.
Thursday, December 11th, 2008 AT 9:32 PM