my truck is hard to start when warm.starter cranks fine and motor does start after cranking over for about 5 seconds.I have a rci fuel cell mounted in box of truck with the pickup fitting mounted on top of the tank.I have a new fuel pump and a clear fuel filter that appears to have fuel in it.the carb is a holly 600 and have set the float bowls to correct hight.the motor fires up fast when cold.motor is a 355 chevy. any of folks have any idea were I should start