Im looking at a 2003 AllRoad 51k and when running no noise but when the accelerator is depressed a clicking noise is can be heard at the front of the engine. I am not sure if this is a normal noise or not.

 

Do you hear the clicking sound inside the cabin (close to the gear shaft)while you're driving it, or when you have the hood open and some one is accelerating the car. If you hear it when you're driving inside the cabin, it's possible that it is the e-brake cable hitting the transmission (I had that problem when I was having mine inspected before purchase).
Good luck!

 

If it still clicks when you let off the gas, but are still moving, it's not the cable. Sounds like a sticking valve to me, but I could be wrong.