The main sympton is loss of power and the engine light comes on steady.
It sounds like that your 3.6 4motion you have is having the failure with the engine. If it was me I would just take it out and run the hell out of it. Pulling hills and high rpms will put it to the test, just run it hard.
Don't depend on VW to call you back they won't. I just got my Toureg back today and It is leaking tranny fluid now, so it's got to go back in the shop. Bottom line VW has produced Junk for the public market and is trying to get out of the mess as cheap as possible.