Stalling when changing gears.

2004 Dodge Dakota 3.7 engine with auto. Trans. 32,000 miles. Vehicle was taken to dealer for oil change special. Dealer cleaned fuel injectors, throttle boddy, de-carboned engine and reset the computer. Picked up vehicle and it stalls like it is not getting enough gas when going from 1st to 2nd, also does it from 2nd to 3rd but not as bad. If you get on it hard and wind it out the stall is much greater. Dealer has had vehicle for 14 days and can't figure it out. Was not doing the stalling until the above service was done. Any thoughts on the problem.