I've got a 1986 chevy C-10 with a brand new GMPP crate 350 290 HP, Edelbrock performer intake and 600 carb. When cold, I hit the gas 1 time and it fires right up and idles. After driving for a few minutes, I can turn it off and it will start right back up,but if I leave it off for 5 minutes, it cranks for about 5-6 seconds before firing off. I have a glass fuel filter on it and I can watch the fuel leak down, back into the tank, when it is off. It still has the EVAP canister in place but only has the line from the tank on it, I did away with the other lines. Could the canister have anything to do with this?