I would have almost bet my paycheck that the ign. switch would have been the problem. Did you check for power at it before you changed the switch? If it didn't have power then and maybe it's an intermintent thing, only other things I can think that may cause that is neutral saftey switch, shutdown relay (try tapping on it and the fuel pump relay) and engine controller. I'm not sure if it's got a crank sensor on that year truck, thats another possibility. Sorry I got no brains until Monday when I'm at work.

Merry Christmas