My 02 4.6is has the same issue. when its in park there's a hissing noise coming from underneath but when I put it into drive or neutral it goes away. Same with the rough idle at a stop but my chain guides were replaced at 106k and I'm now at 130k.

The V-8s don't have an ICV, but I think the 6cyl does.

As soon as it warms up a bit, I'll be using some elbow grease, taking things apart for inspection and cleaning, and looking into it a bit more. Thanks for all the suggestions...

What engine do you have?

If it vibrates in drive when held by the brakes it should do the same thing in reverse with the brakes on.

If it is hard to hear other than when the sound is bouncing off the building at a drive-through, I would check for a vacuum leak.

What are the idling RPMs in neutral and what is it in drive held by the brakes?

Does the sound rise and fall with engine RPMs or go away when it is above an idle?

My apologies, I thot my engine was in my sig, I have it updated now. 4.6... Sounds does not change with RPM increase. I will check my engine RPM's this eve after work, not exactly sure what they are.

Check my RPM's, they sit right around 600 when I'm stopped at a light or stop sign, and don't move, when I shift into N. Is this normal idling range?

Sounds exactly like my symptoms for my 3.0i a little over a year ago which turned out to be the ICV.

For your x tho I would probably start by looking at the easier stuff first like the PCV, throttle body, a vacuum leak, spark plugs, coils, intake boots, add some fuel injector cleaner, heck maybe even just sweet talk to your x haha

Hopefully its something easy. GL!

If the drive-through was next to a building it could be normal sounds bouncing back at you.

While the vibration and the whistling sound may be related, my suggestion is to see if you can pinpoint the source of the sound first.

With the tranny in park I would try to determine if the sound was coming from the transmission or somewhere under the hood. It will help if someone can shift into neutral and back to park so it comes and goes. If you can record the sound and provide a link or put it on youtube that would help. I get the impression it is not very loud, is that correct?

lol I spend quality time with her every day!! ;) I'll start going over the stuff you mentioned, and see what i can come up with. I'll do my best to get a video with some good sound....

BMW E53 X5 M62 4.6L Maintenance Engine Ignition ES#2593257 Ignition Service Kit - 12131703228KT1

Is this kit any good? Looking to do a tune-up, and a ccv change. Or will it be cheaper to just source parts separately?