Hello,
I also have similar issues with my 2 day old 1997 2.0 GTI 8v. I have told it could be something like the automatic choke sensor (not sure of its proper term) as the garage I bought her from claim they have cleaned the throttle body, but I'm not so sure they have......I have been quoted about £15 ish for the part but hoping the garage will fix it as taking her there on the weekend.
I have read this could fix it so will keep you posted