I bought a BMW, E39, 525I from 2003 wirh automatic transmission and I have a big problem with it. While running, when reachs the speed of 45-50miles/h, the rpm indicator start to waver between 1500-1800rpm, 1700-2200rpm…2000-1500 and so on. It goes up and down till it reach the speed of 55miles/, after that everything goes fine. In the moment that the rpm indicator start to oscillate, you can also feel some vibes and a “woove” sound…This happens just when the car is in D mode. If you put it in Sport mode or steptronic, nothig happens and it runns perfectly.
I really need an advise….Can you help me, please? Thank you