i have a 2001 x5 4.4 with 28k on it. the stangest thing happened today. i was on the road entering a parking lot when the engine completely died on me. i then parked the car and tried to start the car again. the car would start but it would not idle. any idea??? i should mention i had just filled the tank with super unleaded and was driving for no more than 5 miles when this happened. any input would be appreciated.

If it dies at idle, but will run at partial throttle, the idle valve is bad