He must have got caught trying to put high performance spark plugs in it. I tell these guys all the time. If you don't know the firing order, don't yank off all the plug wires all at one time.Take one off, put one on. Simple as that. Other suggestions are Georgia overdrive. You can run 110 mph if the grade and weight is right. If the OP reads this....I hope he knows I'm joking around. If you try this and it doesn't go well, don't blame me.
I took my Pro Star that I was running for Hirschbach in for service at the Pro Star Dealership in Oklahoma City. I was told by a fellow driver that I was allowed to turn the truck up to 68. I asked the mechanic to do so. He did. I am no longer employed by Hirschbach.