Electrical problem?

[PHOENIX]

I'm losing electrical and the engine is shutting off.

When this happens I have headlights, but no ignition power, no instrument power, no turn signals, & no heater power.

At first I thought it was my old alarm system. As sometimes it would just start going off while I was driving. I removed the alarm system and it didn't solve the problem. Then out of nowhere it started working again. So I'm thinking lose connection or bad component somewhere. I checked all the wires the alarm was attached to and everything seems good.

Well yesterday I was driving down the street about 45-50mph. The engine died, not sure if the instruments (gauges) went dead or not. I pulled off the road and figured I'd be getting a tow truck. I turned everything off and turned the key. It started right up and I went on my way.

Could a bad ignition switch cause this?
Bad ground wire somewhere?
Distributor (its an MSD, a few years old)?
What to look for, where to start?