c240 Automatic - problems when revved

Hi

I have just got a used Merc C240 Auto 99 model...all looked good when I drove it at slow speed...very quiet engine..
I took it to the motorway and after few miles whn I came back to the slow roads, the car didnt respond to the acceleration, it just revved.

Something u feel when u got dont shift u gears properly in manual transmission....I am not an expert in this field...I fear there is something wrong with the gearbox??

I hope not...wht could this be ?

Whne i came home, I put this in park and revved the engine, I could also feel a heavy vibration (more like the car is being shaken) during high revv...

any help is much appreciated..

Thnx..