I HAD THE SAME THING...THIS WAS MY DIAGNOSIS...FAULTY WIRING HARNESS, MASS AIRFLOW SENSOR. THE STEALER TOLD ME..WHEN AT A COMPLETE STOP....I WOULD PUT A LOAD ON THE CAR FROM A DEAD STOP AND WOULD THEN CAUSE THE ABOVE TO SHORT OUT...MY X5 WOULD JUST CUT-OUT...SOMETIMES IN THE MIDDLE OF AN INTERSECTION....IVE TRIED TO GET BMW TO PAY...TOTAL BILL WAS 2700 BUCKS....LET US KNOW ...WHAT YOU FIND OUT.