I would start with a check of your warm-up regulator (control pressure), and cold start valve. Sounds like you are getting too much, or maybe not enough enrichment with the colder temperatures.

As a quick check, try disconnecting the electrical lead on the cold start valve and see if it still does it.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe