Rattling sound at idle???

[chuy409]

I have this 2008 x5 3.0 and whenever it is around the 650rpm idle range, it rattles that could be heard loud from inside the cabin. If you go outside under the hood, you cant really hear it.

The moment you press the accelerator no matter how light or hard, the rattling goes away. It comes back when the car settles at idle at that magic number 650ish rpm.

If i turn on the ac, the rpm rise up slightly to around 700-800rpm and the rattling goes away.

On cold starts where the rpm is a little bit higher due to being a cold start, it doesnt rattle. Once it warms up and the rpm settles at the 650rpm magic number, the rattling starts.

Doesnt matter if the car is in drive, reverse or what have you, it rattles. Once you start driving, it goes away.

I have thought it might be the air box that could have been lose but i already had someone put pressure on it while I was inside and the rattling continued so it isnt a lose air box.

I also changed both disa valves my thinking being the lose flaps at idle causing some erratic flapping of the valves. The main big disa valve flap was loose while the smaller one wasnt. This didnt stop the rattling.

Does anybody have any idea what it could be? thanks