Is the oil leaking on to the spark plugs and coil boots? I had an issue with misfire in my 4.6 due to leaking valve cover gaskets and oil on 2 different plugs. Ended up changing the plugs, two coils, and gaskets. No issue since.

I feel you on the repairs situation. I have done several repairs including a tranny rebuild. Seems like I have worked out most of the issues for my X and just coming up on 1 year of ownership.

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2002 X5 4.6 Sold
Dinan CAI, TB, Mass Air, Stage 4 engine & tranny software, X-pipe
2004 745Li
1997 Ford Mustang Cobra Vert
1985 Mazda RX-7
13B-REW single turbo 60-1, Haltech, Meth injection, MSD Ignition, and much more
2008 Mazda Speed3 Hypertech Tune