1. checking the temp sensor for proper resistance - I don't have the values in front of me but have seen them on the forum before.
2. cold start valve - mine was working but not long enough ie; it would open upon trying to start (and with 12 v as long as I applied direct voltage) but not long enough when run from the fuel pump/cold start relay (cold start valve resistance was way off 3 ohms instead of the needed 11 or 12) and the 'on' time changed from maybe a 1/4 second to about 1.5 seconds or so at around freezing - now starts well.
3. I also removed and cleaned the idle speed control valve with carb cleaner - forget the real name - was dirty but did not seem to make difference although I can imagine it could.
Good luck. 86 300e 420k km.