Thanks guys, but what kind of issue can exist in this type of scenario?

It seems as all scenarios mentioned would result in oil burning, except for the "ground" reason suggested. I have to research on how to test for a bad ground on the ignition wiring. It would have to be a ground that is connected to all 4 cylinders while not connected to the passenger side bank.

What would cause misfire at idle but doesn't when RPM's are over 800?
What type of issue can go away by increasing RPM's?
What type of issue can exist in the above two questions while not burning oil?

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2000 X5 4.4i w/ 150K miles.