Ok.... I have a 300 SEL with 172,000 miles, new plugs and filters. It has the cold start problem, and I went to a local import shop to have it diagnosed. He said the " mixture control unit was leaking internaly" I guess he could be right but it would seem that the cold start valve would be responcible for regulating this function. I can smell gas when I start it (pump a few times) once warm it runs great...best car I have ever had.
He also said "I need a new vac pump in the drivers side back door for my key fob to work?" but all the locks go down when I use the key the back ones are a little slow. Opinions.....
Can the o-ring on the fuel distributor be the cause of a leak? 500.00 bucks for a distributor is alot of denero. Would like second opinions.

Thank you in advance