engine stalls....

['74super]

ok heres the deal. 1776cc....dual 40mm kadrons. stock heads (i think), empi single qp exhaust...petronix ignition...bosch blue coil....it won't idle. i just finished it up after working on it all winter and it will start and run fantastic if you rev it, but let it sit and it sputters and dies. please give me all possible problems that could cause this. i'm only 16, got into vw's when i was four and built this engine with my dad. glad to be a part of it all, and thankful to have a site like this. thanks for all the help....-nick