Transmission shifts hard shifting from 1st to 2nd and 2nd to 3rd. When the car warms up shifts smoother.
Try a fluid change.
Very difficult for a diy guy on this particular vehicle
This was the first year for the 722.9 transmission . . . which doesn’t have a dipstick, not even a dipstick tube.
This gets filled from the bottom, using a pump and adapters. You can’t even drain out all the old fluid until you knock out the plastic fill tube. To reinstall the fill tube, you have to remove the pan, at which point you might as well do the filter and gasket, as well. The fluid level also needs to be checked at a specific temperature
You basically have to overfill slightly, run the engine, shift through the gears, and check the fluid level at the specified temperature, putting the drain plug back when the fluid flow slows down from a thick stream to a trickle. The the atf is roughly level with the top of the fill tube
This transmission had MANY hardware and software problems, as well. 
in my opinion
Probably would be best if he tells his mechanic to change the filter along with the fluid.