If you didn't have the issue before the work you did, it is most likely this issue is connected and likely a vacuum leak as suggested. Before I would do something like a smoke test or replacing anything, I would try spraying carb cleaner or starter fluid where a vacuum leak may be. If there is a vacuum leak you should hear the idle increase somewhat. The MAF is easy to clean, be sure to use MAF cleaner.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas