FYI: My 2002 X5 3.0i was making whistling sound, like a turbocharged engine when accelerating. I though that was the serpentine belt or tensioner pulley. "Will deal with this later" was my plan. Today however, I started the engine and it choke. As long as you do not press on gas pedal it was shutting off. Hot engine worked fine. Idling was rough though. DISA valve was flapping when idling. SES light is on for other reasons.

It turned out that a vacuum tube, a part of lower air intake elbow that goes to the engine (the last boot that goes to the engine from air intake system) is cracked.

27$ at the dealer and 30 minutes of work and it is fixed.

So before blaming MAF, intake air adjustor (DISA), fuel and air filters, check your intake system for any holes in it if you see symthoms like I did.

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