Try richening the mixture a 1/4 turn at a time until your cold start issue goes away. Have you correctly adjusted the duty cycle?

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Look at this nearby thread:

http://www.peachparts.com/shopforum/tech-help/390036-1991-300ce-m104-98-intermittent-start-problems.html

and read post #5

Duke

I have been steadily leaning the mixture (CCW turn of mixture screw)...I had to go this way to get it to start...

I can not get the duty cycle to cycle - stays on 20% (I think)...I have had trouble with this issue for years! I know about the accumulator - haven't been able to check it yet. I am still having the hard cold start issue and a - seemingly random - stutter from stop, usually after driving for a bit, coming to a stop sign and then trying to accelerate from the stop...

Car will start in the morning, but takes 5 seconds of cranking and then seems to barely catch, and then fires right up!

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE