I've had constant problems trying to drive this car smoothly. When the engine is cold it will hesitate on initial acceleration (which is exagerated on a hill) and sometimes when moving off the accelerator will not work, the revs drop right down and at times the car stalls. When up and running if I let off the accel. and then reapply the car will hesitate. Even when the engine is at normal operating temp. it is impossible to get a smooth take off. I brought the car to a mercedes agent who ran a diagnostic but it showed no faults. He suggested renewing the throttle body at a cost of €1,000 euro but could not guarantee that this would resolve the problem. Any suggestions would be greatly appreciated. The car has 138k miles on the clock.

Have to done routine things like fuel and air filters, sparkplugs and wires? If not I would,replace these items first before even thinking about the throttle body.

Haven't replaced anything on the car yet. Spark plugs and air filter look to be in good condition but I will replace all items suggested before continuing. Many thanks for speedy response.