Hello fellow Mopar lovers..... I have a problem that I can't figure out..... My 69 roadrunner starts and runs perfect on initial startup...... after I drive a while and the engine warms if I shut it off I have to hold it to the floor to get it to retire.....or pull up to a stop sign it wants to die if I don't feather the throttle..... could this have anything to do with a nonvented fuel tank