I have a 2005 e320 cdi> Brought it to mb for service because the car seemed to be bucking slightly around 25-40 mph much like an old gasoline car with points that needed adjustment.

They changed the fuel pump for 1k plus. didn't fix the problem. Next was a egr? valve replacement but that was aborted by the shop mgr who said it was the transmission that required service. That bieng done no change. Next diagnosis was either some control ( sends msg to the torque converter) or that the torgue converter was bad. I have driven some real junk cars in the past and have never had a converter go bad. I discontinued the service at that point. Does anyone have a clue as to what the real problem might be? Thx, chip