Came out to lunch one day and started the truck. It is missing on what seems to be 2 cyl, but could be 1, hard to tell. Put it in gear and the truck is shaking, but by the time I got out of the parking lot it was running perfect again. I thought it was odd, but it's the first time I did it so I didn't think too much about it. Well, about 2 weeks later (last night) I bought a camper and towed it from the dealer to a parking lot about 5 miles away for a pit stop. When I start the truck back up, it is idling rough again. Light acceleration in the parking lot it's pretty shaky but I couldn't tell if it was 1 or 2 cyl down. Once I pull out onto the road it's running smooth again and the rest of the night it's perfect. Is this just a glow plug not heating up right until I get a little warmth built up or something else? It's only happened the two times, and both times once I get on the main road it fixes itself. Once when cold, and once when warm. Ideas?