If the crank sensor is of unknown origin...that would be suspect just because aftermarket electronic things never seem to do well in our cars.
Those lights are pretty common, I think, and they indicate more than you think just because you can also 'manually' control them. If you search for them in a 'thread title search' I'm sure you'll find some useful threads.
I remember a few threads with cutting out while driving. It can just be loose cable on battery too, corrosion somewhere on one of the major grounds?
As desperate as this sounds, in comedy, 'likes' and 'views,' 'friends,' and 'retweets' really help. If I've ever helped you, please help me by friending, liking, viewing, and retweeting. It makes others think I have a following...it'll take you a minute or less. If you could, I'd really appreciate it!
A recent set--NSFW audio: https://youtu.be/_dcxcZfD6dg
Mangofy your E46!