Well here is the deal, I have a book of the schematics of all the wiring, I just don't have a working scanner right now. Ignition switch was a good call, but you should have other accessories working too. Headlights don't run in the ignition, they are live anytime the switch is in the on position. Horn, brake lights.. etc. Because the problem isn't Isolated, I'm thinking it COULD be something more obvious. How are your grounds? Battery Cables? If you have a set of jumper cables, clamp one to the Negative post on the battery and then ground the other side onto something that is grounded very well. It sounds to me, that it could very well be a grounding issue. Especially cause it isn't regular. You can try to turn something on, headlights, or leave the keys in the ignition for a buzzer, and wiggle your terminals and cables. If you wiggle something and you see the lights flash on, or hear the buzzer, you might be able to isolate the problem that way.