Transmission

I have a friend who has a 1998 Jetta GL (2L 4cyc A/T) with about 45000 miles on it. For some reason his transmission hangs as he speeds up (usually will go up to 4k rpm and take about 20 seconds to shift, but it’s not that hard of shift when it does). Pretty much my goal this weekend is to change the speed sensor and the tranny fluid to see if this will solve the problem. If anyone else has ran into this problem and has any information to share I would be very grateful.

It's a complicated job just to change the fluid. It takes special fluid also.