I had this problem last week. Rough idle, car vibrating at idle like it was going to shutoff. I assumed it was the spark plugs and brought it to my brother's shop. He diagnosed it as a faulty intake manifold runner valve adjuster. $185 dealer cost.

04 530i manual 100k

 

Thanks, I need to really get this done, it's very very annoying. And since it's automatic, it feels like the car just want to launch forward at times.

I'm glad it's not a costly repair.

 

RPM play at stops is a very common issue; one I am also dealing with currently. I am coming from a 530i with a N52. I still have this issue even after changing the plugs.

After speaking with some of the techs, rough idling is most likely associated with a vacuum leak.

 

Well I got my car back from my brother, no more rough idle and it drives like a dream again.