slimjim

Good morning all. Newbie here with a problem 2002 C180 classic (automatic) with the 111 engine. Long story... when I leave first thing in the morning for a 200km round trip, the car starts off flawlessly for the first 5km or so. Thereafter, between the speeds of about 85km per hour up to about 140, the car seems to surge/hesistate or feel like it's having the odd misfire when accelerating. It often comes with a sort of brrrr noise coming from underneath/the rear of the car whilst it's misbehaving. Have had a full on diagnostic/interogation done on the vehicle which shows all clear, changed the plugs, fuel filter, etc. had the gearbox checked, no change. Tried driving with the ESP switched off, no difference, as I thought maybe one of the wheel sensors was faulty. One of our local Merc experts says it's a mystery, and he needs the car for a couple of days to investigate. Unfortunately, I can't really spare it for that long. Any ideas anyone?