i had this problem, im 99% sure its the cam sensor. I had the dealer do it, as i had just got my car, and being 17 at the time, hadnt had much experience with it yet.
i dont know why the dealer told you to change the plugs and wires on the turbo passat, cuz the 1.8t utilizes direct spark ignition, each coil is fed directly to the plug, it has no distributor or the like. its all electronic.
like i recommend to everyone here, check the vortex, it has a plethera of info. Biggest auto enthusiast website on the net, and more info than youll ever need