I own a 1991 300SL also. I have 95K miles. Here's my experience. It all depends on how cold it is when I do the cold start. On my car, if it's below 45 degrees when cold started, it runs just fine. But if it's say 50 degrees or above, it will run lean, lack low end power, and stumble a bit. After about a minute of warming up, it runs OK. So, it's outside air temperature sensitive. Of course, the warmer the outside air temperature, the more quickly it comes up to operating temperature. There's an awful lot of complex stuff happening while an engine warms up. Since I hate to leave my car at the dealer so they can start it "cold" once every 8 hours, I just tolerate the warm up period. My condition doesn't sound as severe as yours. I'll be watching this thread to see what others have to report. Tod

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