I glad to report that I have finally found and fixed the issue. After monitoring the issue for LOOOOOOONNNNNGGGGG time, I noticed that though the pending code of a cylinder misfire was a result of the rich mixture and long cranking time, it did point to a potential problem. Every time the misfire was on cylinder #1. I had considered that I may have a leaky fuel injector, but had ignored this since it cranked fine after sitting all night. Apparently the leaky injector would leak enough fuel in the first 30-45 minutes to make the car hard to start, but would stop leaking when the fuel pressure went down sufficiently. The fuel would then evaporate allowing the car to start normally after sitting long enough.
I replaced the fuel injector on cylinder #1 and all is well. Hopefully this will help someone in the future.
Later, Steve
2017 BMW M4 Comp
2011 BMW Z4 35i 6sp
2001 Porsche 911 Turbo 6spd
2004 BMW Z4 3.0i 6spd
2001 BMW M3 6spd
2018 BMW M550i X-Drive
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