Rough idle and hard cold start
A couple of things happening on my '88 528e.
1. Before the cold truly set it, the car starts after a couple of tries. Then after hitting a steady state idle, everyone once in awhile the idle speed will drop a few hundred RPM and then jump back up.
2. With the frigid weather in WI, I came out in the morning to my garage (~50 deg F), and she started up OK (typically the same) as any other morning. Drove to work, and parked outside. Temp about 12 deg F all day. When I came out that night to go home, it was very difficult to start. Turn over fine, but just wouldn't fire off right away. Took about 10 cranking tries to get her going. Once started, still had the rough idle (dipping a few hundred RPM's for a second or two).