My car keeps stalling



I have a 2002 BMW 325CI convertible automatic with 42.000 miles on it. It has an occasional habit of stalling when I am in a parking lot and I am going very slow and turning the wheel to either enter a space or backing out of the space. It has also done it when I am making a U-turn. I have had it in the shop and they can’t seem to find the problem. Then have replaced the mass air sensor and did a fuel injector service. They have recommended a number of “possible fixes” but can’t really pin down the problem. It has been in the shop 4 times and I am hesitant to spend tons of money eliminating one possible at time. Any suggestions?