BMW 325XI Does not want to stay on when started

Check engine light on

Have the computer scanned for code/s-you have a problem within the engine management system that caused the CEL to turn on-This is your starting point of diagnosis, finding out what's going on

As well as having the aforementioned scanning performed, an underhood inspection might be revealing. Often starting and stalling, as your post suggests, is due to the intake boot (from the throttle body out to the air mass flow sensor) having been compromised, especially where the boot diverges and goes to the idle air control valve. After the fault is corrected, the codes need to be cleared. Let us know what you find out.

Is there something new to report?