Could this be the ignition switch or switch wiring harness problem?
As the switch wiring is pretty much stationary all of the time I would assume it is the switch that has failed. That said, if your truck is parked somewhere that mice have access to it, you could have had some chewing of the wires and an intermittent short somewhere in the harness. Electrical problems are always a giant pain to diagnose, good luck!
I would certainly check the wire harness and the connections but it sounds more likely to be the ignition switch itself. An error that many people commit is to have too much weight on their ignition key ring, which often leads to premature switch failure.
