Ignition Problem

[bcoke]

When I turn the key it fires up, but when I let the key go it dies. It'll stay running if I back the key off just enough to have the starter motor stop, but as soon as I release it all the way the motor dies and there's a sound that sounds like the engine is slowing itself down (sounds like engine braking for those stick shift drivers out there).

I'm pretty hopeless when it comes to electrical wiring of these cars. I googled around about this and read about the ballast resistor burning up and causing that problem or an ignition switch problem. I checked for the ballast resistor wire but since none of the wiring is stock I couldn't find it. Don't see any burnt wires though.

For some context I have a 72 K5 with an IROC Z28 TPI engine. Lists of problems that I've fixed fairly recently that deal with electrical:
- battery drain - replaced a bad temperature sensor that was always going to ground with the engine fan (electric), fixed by replacing the sensor and putting the fan on a manual switch

- headlights blew out, replaced the fuze and the bulbs, no luck, had someone rewire the headlights (can't stay on hi beam too long though or the switch will get hot and the lights will go out)

- starter motor crapped out - replaced it with the standard one for an 89 IROC from autozone

This thing has been one problem after the other so trying to get this latest one solved. Any help would be greatly appreciated!