I dropped the truck at the dealer yesterday afternoon (very hard to do). It ran like crap all the way there. This morning the dealership calls and said it runs fine. They hooked up their diagnostic equipment and it showed nothing. I asked them to take it for a long drive, they did and said it ran excellent. Then they sprayed water on the engine and were able to get a misfire in #3. They let it run for a while and it cleared out. They said it could be a coil but it tested out ok out of the truck. They don't know what to do as it runs good now. I am concerned that the problem will show up again but what do I do? You can't fix what doesn't appear to be broke. We have had some very humid wet weather here this weekend, perhaps it's related. The diagnosis charge is good for thirty days so if it comes back I won't be charged again.

 

Replace coil #3 and run it until it quits.