Car dies in "run" position

Check the ballast resister since you have the dual ballast resister. The 12 volts positive goes into the connection where the ballast is connected together. One ballast has approximately .5 ohms and the other is approximately 1.5 ohms. The engine starts on the .5 ohms when the ignition switch is on "start" and when you turn it loose it goes to run position and runs on the 1.5 ohm side. I bet the ballast is either backwards or the connection from the .5 to the 1.5 side is broken.