1998 Trooper 3.5 V6 Accelerating @ gear problems

[swissdriver]

Hello @ all

a friend of mine has a 1998 Isuzu Tropper 3.5 V6 with Automatic.
The Problem he has is really strange and i can not find it here again.

When he comes to a stop and want to accelerate from 0 the engine rpms goes up but the car don`t move unfortunetaly one wheel drives and makes funny noise and bang the other one goes to and then anything is fine.
The problem occures from time to time.
The tranny has new oil ( Dextron II ) one year ago but not a new filter.
The Enginelight ore anything else doesn`t blink there is no error code .

One men told us to buy a new transmission ??

Greetings