Weird idle issue

[Khswart]

Hey all, I've been having an issue with my 2004 330i for a few months now and I cannot seem to figure it out. The car idles perfectly at around 700-800 Rpm when in park or neutral, but when I put the car into reverse or drive, the rpm drops and goes to about 500 and will vibrate and shake the whole car. when I turn the AC on, while still in drive and stopped, the rpms will go up to maybe 600-700 and the vibrations will go away for the most part. Also, this doesn't happen immediately when the car is started in the morning, only after about a minute once the car warms up a bit and the rpm drops. I have cleaned my MAF sensor and ICV already, and the DISA was replaced about 6k miles ago. I haven't noticed any holes in any intake boots or vacuum lines, and I can hear a loud hissing noise coming from around the DISA/ICV area of the engine. Any help would be hugely appreciated.

[Pelican Parts]

Get the codes read, it'll tell you exactly where to start looking. Sounds like a spark plug fault or dirty injectors. Is there a momentary 'jerk' that the car makes when putting it in reverse or drive after it just warmed up? If that's the issue, check out the link below!

http://www.pelicanparts.com/BMW/tech..._Injectors.htm

[MIKYZZ4]

Sounds like an intake leak. Scan for codes.
Fuel mixture codes will confirm.
Perform an intake smoke test.

[Khswart]

I'll continue to look into the things you mentioned, but what would cause it to drop in rpm's only when put into reverse or drive?

[MIKYZZ4]

The codes will indicate if the transmission EGS module senses a problem.