318 won't stay running

Check the wiring around the ballast resistor and replace the ballast. A failed or disconnected ballast resistor shows exactly the symptoms you describe.

Don't get just any ballast; the resistance is critical in the Mopar system. The MSD 0.8 ohm ballast is close to the OEM ballast. The next best commonly found ballast is a BWD RU19, but you should try to get the OEM (eBay) or MSD.