I have a buddy I put a new motor in his 94. 350 TBI. The truck runs great but if he parks it for any length of time, like over night, the gas will drain out of the line and he has to turn it over a bunch to get gas back to the throttle body. Once it starts it will run fine sometimes with less performance for a few minutes untill it warms up. My first thought was fuel pump but is there anything else that might cause the gas to seep out?