As bcredliner mentioned, there are literally multiple issues that can cause a ruff idle. If you have not done so lately, I would recommend a tune up - plugs, check coils, clean throttle body, all filters (yes fuel too) and pull all codes. Yes even the pending fault/failure ones. This will give you a base line. It will also expose vacuume leaks etc. if your year has replaceable coil boots- replace them with the correct brand boots (not one size fits all).
Repost when you pull the codes as it will help those who offer up assistance from a far to understand what is going on in your engine.
Example: I just did this on a E39 wagon and the results were to be perfectly frank, were amazing. Idle, tip in acceleration, wide open performance, fuel economy, and slow speed modulation all became perfect.

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2005 X5 4.8IS
The Blue ones are always FASTER....

Current Garage:
2005 X5 4.8is
2002 M5 TiSilver
2003 525iT
1998 528i
Former Garage Stable Highlights
2004 325XiT Sport
1973 De Tomaso Pantera, L Model
1970 Dodge Challenger T/A 4 sp Alpine White
1970 Dodge Challenger T/A 4 sp GoManGo Green
1971 Dart Sport, “Dart Light” package
1969 Road Runner 383
1968 Ply Barracuda 340S FB Sea-foam Green