I run a sprinter but an 05 model. So far have had very few problems. Curreent mileage is over 200,000 miles. Great fuel economy and have hauled over 3000lbs in it (wasn't over weight) and still going.
However on the flip side. A fella with my old carrier had more problems than you did. He spent over $30,000 in repairs and that's not counting warranty repairs. His was a 2004 and everything broke. COuple of torque converters, couple of rearends, couple of drive shafts and turbos, fans, sensors, front end parts and more.
I have been a fan of european vehicles for years and this proves that you don't need a 400hp motor in a van to haul with. This 2.7l is good and the turbo works great. Now the transmission, well I find that a weak link and the dealer will not fix the rumble strip vibration from it. So I keep running and changing the fluids etc. Definitely the transmission is not upto taking abuse. There GM has everyone beat hands down. My last GM had half million on it and original transmission, no rebuild. BTW also had original tie rods only replaced the ball joints in it (lubed the hell out of that truck). Mechanics could not believe mileage and still origianl frontend parts. Tie rods still tight when I sold it.
So i think you got a lemon. For me so far great buggy. Sprinter has been a different one to run and service as there are quirks, but pretty good overall. BTW if you get another one, find a mercedes mechanic outside the dealer system. I get better service, cheaper, and some mb knowledge that the dealers (dodge especially) don't know or won't tell you. My dodge dealer sucks big time. can't even sell me parts fast as can't figure out what's in it (with VIN). So poor dealer network and support from dodge but for some of us a good work vehicle. LOve the fuel economy, especially with these higher prices.