This almost sound like a ground problem but with human interference, that is speculation.

Stop trying everything and anything, you'll just drive yourself nuts.

Let's break this down to systems. Stumpy is right, jumper the brake switch, what happens?

Yes he's right about the switch not always activating the park lights but I'm not sure what year that changed.

Stumpy is also right thyatvthe park fuse is hot on both sides when the headlight switch is set to park.

Short version, look for wires and connections you may have bumped while changing the master. It's more likely that you did something than wires crossed whom you changed the master.