Crank sensor would make sense, if you had the car just stopped and there was no fuel trim codes. I am much more likely to beleive that the mass air flow has gone queer. IF it is not functioning correctly, that could be fucking up the mix.
Lately, I have noticed that a lot of the Bosch M.A.F.s seem to be going bad. Most of them were on volkswagen, but this could happen to the Benz.
On another note, I wonder how these machanics were diagnosing this condition. Did you lose spark? Fuel delivery? Did anyone check fuel pressure and spark, while trying to replicate the issue?
There have been intelligent things said by all who have posted, but the professionals that were mentioned did not seem to act as such.