This problem reoccured when I had my oil and filter changed at a fast lube. When I pulled out of their parking lot the engine had about 50% of normal power. I watched a mercedes mechanic a month ago tear off the metal cap on top of the fuel injector pump on the back right of the engine and open the set screw. This helped at the time but I tried to adjust it out even more a couple of days ago with no response. Thanx again for your help.