i had problems with my mk2 gti 8v.it kept dying at lights and junctions for no particular reason.always started again but someone suggested the idle valve so i changed that but to no avail!!
in the end i got a mobile tuner to look at it who works on a private collection of classic ferraris,lambo's etc and he used to sell golfs so he knows his stuff.
£30 later and i got 42.9 mpg on the way to manchester from devon,more than happy with that.its levelled off a bit now and averages about 38-40 mpg on long trips.
cracking car,love it to bits!!