I hope someone can help me.

2001 Cherokee Sport, ever since it's turned cold there's a whistling coming from under the hood. It's not when I first start it and take off, but after about a mile or so the whistling starts. When i let off a little the the gas you can here it but it's real low pitched, the more i let off the higher the pitch gets and it gets pretty high pitched when I let off the gas completely. I can press on the gas a hundred times and it does the same thing. If I stop and let it idle, the whistling eventually will stop too only to return again once i start driving, and then it's the same routine.

Any advice?

Thank you in advance,

Led

 

Vacuum leak? Check all your vacuum lines are attatched.