GTI power/ HID light out

Ok,so here goes bought a GTI 2008, long story short, when I get my foot in it on the freeway after a few seconds its starts to hesitate with a jerking motion like its out of fuel. this only happens when I try and go over about 80mph.
Just happened yesterday when I start it up the left headlight flashes then goes out, the light on the dash comes on and stays on.

Any help for all...