Can someone help? I need to drive my dart tomorrow

Could be.
It should control the voltage so it goes from 13.2 to 14.5 Volts out.
The electromagnetic coil pulls the arm down when it gets power. When power is weak, the arm moves to the top and closes the connection from the in (ign) to out (field +).
When the electromagnet gets a little more power, it pulls the arm to the middle. Electricity goes through the two parallel resistors (on the bottom) to the field.
When the electromagnetic gets even more power (such as high rpm an low demand), it pulls the arm down and momentarily grounds it through the third resistor underneath.

That doesn't change the two other issues we've identified. 1) High resistance in the wiring. 2) unknown wires in the main power circuit.
There is probably resistance in the bulkhead connector. It may be at any of the terminals or crimps, such as at the ballast resistor, the start switch. There also may be some in the grounds, body to battery negative or engine to battery negative.