I would say everything from a clogged fuel filter to a clogged air filter and many other things in between. Can you give a better description of perhaps when it doesn't accelerate well? Like when it's hot or cold, does outside air temp. play a role, etc. etc. Have you checked the timing? Tune-up recently? On and on........

Maybe if you can fill us in on what you have checked, replaced, and conditions when the acceleration is low we can help.

I see your a new member........Welcome to the best Mercedes help site on the net. The knowledge from the members on this site is staggering so good luck and hopefully we can help you!

Dale