Common issue in N63 and S63 engines with 60k+. Most of the time it's an easy fix:
Starting in order of what to check first:
Vaccum lines
Intake hoses
Spark plugs
Coil packs
CCV lines
Wastegates
Diverter valves
Pressure converters
Injectors

9 times out 10 it's either the plugs or coils after any possible vacuum leaks or pressure leaks have been eliminated. Get yourself the foxwell nt510 with the BMW software or bimmergeeks pro tools so you can know exactly what's going on...if it's under warranty great ..if not be prepared for the M tax....for example, you can replace all 8 spark plug and coils for less then 400 yourself and it's super easy to do (coils can be removes with just your finger!!!). But the dealer will charge you 1400 dollars.....