I have had several cars come in with vacuum lines pulled off the back of the intake manifold after having the trans removed. The idle will wander with a
vacuum leak. The angle of the engine when removing the trans can stress
lines and cause them to slip off or fail.
look at the big plastic purge line coming from the purge valve to the drivers
side of the engine above the p/s pump. That one loves to pop off.
I would have to say that if your car ran like crud after they touched it,
then they should have another look at no charge.
Good luck
DR.D

__________________
Dr.Diesel -
Shop Foreman
Master Guild Mercedes-Benz Technician.

Think the dealer is expensive? Do you know how much it costs to train a dealer tech? Or buy the required MB special tools to have on hand?