help with 68 lemans
 

have a 1968 350 2 barrel lemans I have replaced the distributer cap, rotor, points,plugs,plug wires, air filter, oil, oil filter, Started it up and it ran for about 30 minutes and then died Everytime you fire it it starts and dies instantly Ran a wire from the positive side of the battery to distributor side of coil ..it runs but back fires and dies as soon as you take the wire loose.