1003 525i M-series won't start, sometimes
My car starts and runs fine, but without explanation, sometimes it won't start. When it won't start, the whole engine jolts from left to right, like it is hung up. (I've noticed some smoking from the tailpipe recently.)
I've learned if I take the key out and wait a minute, it may start. Other times, it won't start so I am concerned about getting stranded.
Any ideas of where to start looking for the problem?