car stalls when stopping on a red light or waiting to turn on a stop sign on 2001 BMW 325Ci

after driving on a highway and exited, when i stopped on a red light, the idle speed dropped and the engine stalled. This happened twice. Also when i was driving on a highway and hit rubbernecking traffic, the engine stalled. My nephew who used to work at BMW dealership checked the disa-valve and the fuel fuse which are good. He suggest to replace the idler control valve but it is very expensive. May i know if we are on the right track, or is there any other underlying problem. Please let me know and thank you so much.

1 answer
you need to find a reputable BMW specialty shop that can diagnose this for you. without proper software or diagnostic tools, you're just guessing on what's wrong.