Hmmm...I have the same idle fluctuation problem...but mine acts up in D or R (especially R)...more prevalent in warm weather than cold.

Swapped out the air flow unit with a new one, and the problem persisted, so I returned the new one.

Was I wrong for doing this?

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car