[hofftemp]

I have a 2005 F250 6.0 King Ranch FX4 Off Road with 206,000 miles on it, running a Bully Dog Pup at 90%. All that has been repaired is EGR valve and a fuel injector control modual. It runs great most of the time, it has started, sometimes, but not all time, idling rough and misses while driving at steady throttle, smooths out on hard acceleration. The miss or cutting out is just like an old style distributor with bad points or bad plugs. I pull an all steel 20 foot heavy duty car hauler, usually with no more than 7000 pounds on it, very seldom drive over 65 mph, so I don't think I am overloading it. There are no codes and no check engine light. What do I check first?