65 coronet wiring issues

I am working on a 65 coronet with a 440 auto, runs ok till u turn on the Headlights car will stall :protest: so when u try to start the car after it stalls it won't turn over with the key ? But u can jump the starter relay and it wind over with the key on but won't start ?? After about five mins the car will start with the key !!! So with keepin ur foot on the gas and you pull on the headlights the car will run but very rough !! I'm at a loss not sure where to start on this any one have any ideas. Thanks mike