Subtle engine problem

[peperdilo]

I am hoping someone can shed some light on quite a subtle problem with my car, I have a 2006 clk 220 cdi, and when you accelerate lightly up a hill the engine seems to pulse or hesitate slightly, and you can see the rev counter fluctuate by 100 revs or so. Once your speed is constant it stops.
Can anybody help with this.

 

[st4]

Its just your torque convertor slipping. Completely normal, its never fully locked up and even on the flat if you lift off you'll see a slight drop in revs for no drop in speed.