help me help a friend shifting problems

my neighbor has a 96 jetta gls that has been a problem. has trouble shifting in all gears. at first i thought it might be a vacuum leak and found a couple of hoses that were broken or worn through, fixed them up and hoped for the best but that didnt work. it shifts rough from 1st to 2nd 2nd to 3rd alright and 3rd to 4th only when you let of the gas a secong and then give it gas its a automatic and hopefully you can help me out with hints or ideas. thank you for your time

When I run into this type problem it's almost always the transmission fluid. Do the following:
1. Make sure it has the right kind of fluid.
2. Change the fluid if it's been over 20,000 mi.
3. Change the transmission filter if you have to change the fluid.