I had a stalling problem with my '01 X5 back in '01. It would stall occasionally when slowing down and making a turn. It would stall in the turn.
It was fixed by a reprogramming of something as determined by the dealer under warranty. Sorry I know this doesn't really help because I don't have all the details in front of me about what they reprogrammed. After Wednesday I will have access to all the records (when the X5 gets back from the airport parking lot) and I will look it up if you are still interested.