Losing switched power and other #$%&^# electrical issues. HELP!

I don't know how you ran it "before." Using the yellow wire could cause a feedback situation. There are only so many ways to get around this, as the "run" wire has always gone cold during crank

1....Rewire the brown so it's functional and jumper to the blue "run" You can do that either in the bay or under the dash

2....you could run a diode between the start terminal (yellow) and the "run" to isolate them, but with RadioShXXt being pretty much dead, just getting a diode is tougher.

3....you could parallel a second relay to trigger with the start relay and use the contacts to route starting voltage to the MSD