I have been having a very similar problem with my 1.8T for about 2 years now (although mine would sometimes completely cut out, try loosing power steering and power assisted breaks at 80MPH, yikes!)http://www.golfgtiforum.co.uk/index.php?topic=52613.0No fault codes, new MAF sensor and temp sensor fitted, various other theories persued; still no joy. My latest round of problems seem to be battery related but I don't know whether there is a link to the ongoing intermittent power loss issues.http://www.golfgtiforum.co.uk/index.php?topic=106378.0I do recall noticing that my battery warning light would flash on while the car was having one of it's moments, have you niticed this?