Fresh Startup Procedure.

Mmmmmm.... you have better test the ignition voltage to the MSD while running. It should only be no more than .5 volts lower than the voltage measured across the battery terminals. The ignition switches can go bad, but the wiring through the bulkhead connections in the firewall is a VERY common place to have voltage loss; the terminals get corroded badly. You had better check that and the connections in and out of the ignition switch.