Any Ideas?

I picked the van up a week ago Friday, had ALL fluids flushed and changed, tranny, rear end, coolant, oil change,both fuel filters and air filter. Ran fine when I took it in, was just time to do that stuff. First thing I noticed was it held in gear longer than normal then snapped into the next one. OK, I'm thinking maybe with the flush of tranny it had to re-learn shift points. Didn't drive it all week, have another van I drive to and from work to save the diesel for pulling my trailer. Last night (this Friday) we took the Ford out to dinner, ran fine going except for those shift points, then, coming home it lost all zoom and finally quit running all together. Coasted off the road, stopped, waited a couple of minutes and then it started again and I drove on home. Today, got up and was going to go to the dealer to see if there were any codes, well, it ran perfect.....shifted smoothly when it should and had plenty of power. Made a quick stop and after restarting it, it was back to hanging in gear and then snapping into the next, then once again, all umph went away and it quit running again. Couple minutes, got it started but not much power then dead again. Couple more minutes, same scenario. Gave up because it was shaking real bad when I got it running that last time and called the tow truck. An hour and a half later when the tow truck showed up, we actually drove it up onto the tilt flat bed at one heck of an angle with power to spare. Van is sitting at the dealer for Monday for the mechanic to look at. By the way, it's an 05. Any idea what they might find? Something the servicing caused I hope!