ballast resistors

Ballast resistor was designed to add longer life to a points ignition system by dropping the voltage down to around 9 volts. When you start the car the ballast is bypassed giving a full 12 volts to get the car started, when you release the key then you're running through the ballast which, like I said is decreased voltage.

That's why sometimes when you start the car and release the key it dies, usually indicates a bad ballast.

To the OP, is this the case or will your car idle and then stall when put in gear?