My BMW has had this problem since I purchased it. When I'm at cruising speed 45+ the car seems to have a stall feeling or bump feeling. It seems to disappear if I accelerate but when the throttle relaxes the surging or stalling feeling returns. I have never been stranded and my mechanic says not to worry about it tell something gives a code etc he can trouble shoot. More annoying than anything. Anyone have any ideas or seen this before?