If you believe it is a fuel supply issue you have a Fuel Tank Screen, a Fuel Pressure Relief/Overflow Valve and of course the Fuel Supply/Lift Pump.
There is 2 threads on rebuilding the type fo Fuel Supply/Lift Pump that you have. My notes are kind of messed up but I think this might be one of the threads.
606 Fuel/Lift Pump Rebuild
OM606 Fuel Pump Rebuild - PeachParts Mercedes ShopForum
Some of the Fuel Pressure Relief/Overflow are said to have a plastic piece inside of them that warps or fractures. There should be a ball bearing, the plastic piece and a spring inside.
Is the turbo boost pressure reaching the ALDA and is it the correct boost pressure?