Classic example of oil fouled plugs. Confirm plug is firing after coil replacement.
If yes, then you need to do a compression test and a leak down test. A bore scope can be a problem solver for your vehicle here by looking into the cylinder for bore scoring, valve sealing and a peek in the intake side will show if oil is leaking into the intake manifold.

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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