I have terrible news. Your tranny is spent. I had the exact same symptom as you. Tried every remedy, changing trans oil and filter, blah, blah,blah. The reason is the torque converter is slipping, grabbing, over and over. Did you notice in sport mode it's better? The only real fix is torque converter replacement.

My shop charged $750 for trany removal and install. And $2400 to replace torque converter and all clutch plates and valve body. They said all looked "ok" but torque converter was smoked.

Sorry to tell you the bad news, but do a search here for trany problems, you'll find lots of people talk about identical issues you are having.

__________________


Pro motocrosser since 2005. First time BMW owner.
2002 4.4 E53