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.