Update - Brought to dealership last week, they claimed it was a corroded wire from battery cable to ECM/PCM. Well guess they were wrong. Truck rode fine for a week, then our friends borrowed it to take it to update NY this week. On the way there, Sunday, the check engine light went on, same thing, shaking, driving slow. Today he calls me to tell me the truck won't even make it up a hill. Great, 5 hours away!