[cleanspeed1]

You didn't specify whether it was gas or diesel. First thought that came to mind is that if it is drive-by-wire, there might be something wrong with the accelerator pedal assembly ( it's a big rheostat ); the next thing deals with whether it has traction control and one or more of the sensors is malfunctioning and sending a bad signal to cut the power back. But it's all guessing; you need to plug the old girl into VAG spec diagnostic tool and run a check.

Another thing, and it may seem kinda dumb, but make sure your floormat isn't in a wierd position that can limit pedal travel.