I have a 86 dodge 150 with the 318 it is carbed. In the morning when i go and start it, it cranks and starts fine but stalls after 20 seconds. Go and start is again cranks and starts fine kicks into high idle then stalls after 3 mins. Start it for the third time it runs and stays running. Starts and runs fine after it is warmed up. I think that the fuel is draining back to the tank if it sits to long. The fuel filter has been changed recently. there is a third line on the fuel filter that goes back to the tank. Is there a check valve in there somewere or a pressure relieve valve in that line. Can i go to a nomal to way filter instead of a three.