The short has been found! Believe it or not, when I bypassed SBF 5 power was sent through four relays, fuel pump, main, A/F O2, and electronic throttle control, along with two terminals of the ECM, out terminal 4 of the main relay and to the power supply for the pressure control solenoid and the drain valve of the evap canister.
Although I did not find the actual short or wires burned together, I did find evidence of where the wire was heated and discolored as it came through connector R57. It had also been hot enough to melt some of the sound deadening material before the harness went into a grommet and out the floor. The reason I couldn’t see the actual short is because that section of the harness is routed above the gas tank, then goes to the evap canister. I cut the wire at R57 and made sure it wouldn’t contact anything and disconnected the pressure control solenoid and drain valve.