Hey Abbas. I am not sure if the summer/winter differences are that dramatic. Maybe a very chilly cold start would differ from a warmer one, but not too much. What strikes me about your question is the 1200 RPM "for a couple minutes". As Rodd mentioned, 1200 is pretty high -- even for a couple seconds, I'd say... Mine is set to idle slightly higher than the called for settings -- and on start up is maybe 900. Never over a 1000. I wonder if there is something else raising your idle -- maybe throttle linkage sticking somewhere?
James
63 230SL