528 - 1997

Hello- I have 1997 528i with 300 miles left on extended warranty. I have a horrible high pitched whistle when idling heard best when in covered drive through. Dealership has had the car 3 times and 3 excessive checks from me *still have problem. I don't have tools and/or skill to repair myself. Any suggestions on repair and replacement of anything before warranty runs out??? 143,000 miles, original owner, second BMW THANKS!!!