Just to clarify, when I insert the coils into their respective spark plug holes and press down, they "bounce" back up maybe 1/8". They never actually seat onto the spark plugs. I had to rely on the tightening of the nuts to get the coils to fully seat against the heads. All eight of the coils behaved this way. I don't remember this type of behavior on any of my other BMWs. Does this sound like it could be behind my engine's rough running?

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2003 X5 4.4i
1992 Porsche 968
2007 328i
2014 Subaru Forester XT