I have had the worst problem, while riding down the road like 60 mph I will hit a bump and the truck will try to shut off but keep running. Eventually, it got so bad that it totally shut down and the wires connecting the key switch and run through the fire wall, ( primarily the red wire that goes to the post on the fire wall, fuel pump hot?) have melted and fried the key switch. I took it to a shop the first time after getting towed and he replaced the key switch and some melted wires, but after about a month it happended again, always after hitting a big bump. Has anyone ever had a similar experience. Don't just tell me there is a loose connection or wire somewhere because I already know that, I'm looking for something more specific, because I can't find it. The Jimmy is parked at my house for now. So I have time to work on it.