Re: Whistling noise when you take your foot off the accelerator
My wife's 2012 Jeep Compass had this slightly. Happened after I changed the engine air filter the first time. Could never pinpoint it or make it go away. Prior to that, the only time I ever encountered it was with not-fully-enclosed C.A.I. kits, like the K&N.
I would check the engine air filter assembly, make sure its all tight and sealed.
2014 Jeep Grand Cherokee Limited 4x4
5.7L Hemi V8, Luxury II Package, Navigation
Hemifever Tuned, Billet Catch Can, 265/60R18 Hankook Dynapro ATMs