Help 80 TDI Terrible Cold Start White Smoke

[StompOn]

right here we go my 80 tdi is a pig to start in the mornings just now a good 30secs of turnin over untill it springs into life and a load of white smoke comes out the back first thought being white smoke cold burnt diesel so glow plugs so i replaced all them with denso ones still had the same problem so then i went for the relay 202 i got a genuine proper one from audi and no still same problem once its been running for 5mins or so and you stop it it will start with a flick of the key no problems no smoke my head hurts on this i checked all the fuel pipes in the engine bay making sure all is tight no fuel seems to seep back thru the system when ya switch it of im well ad truly stuck anyone know of anything? any help would be great thanks