[Glagulator]

Welcome.
Unplug the FUEL HEATER and WATER IN FUEL electrical connectors on the Fuel Filter Manager.
See if anything changes. Inspect those pigtails where they enter the FFM for bare wire and shorts.

 

[Glagulator]

Try unplugging the MAP sensor and the BARO sensor.
See how it runs.
Have you removed the filter harness from the OS?
Looks like the 5v. circuit is shorted.

 

[Glagulator]

You might check the A/C clutch diode.
From the 1995 FSM.

“The A/C Compressor Clutch Diode is connected across
the terminals of the A/C Compressor Clutch.
Whenever the clutch is de-energized, the magnetic field around it
collapses, generating and induced voltage in the clutch coil.
The Diode provides a path for the current resulting from
the induced voltage so that other circuit components are not
damaged.”

The diode is in the harness about 6” from the clutch connector.
To test - remove the A/C relay in the UHFRC.
Check at the clutch connector for continuity on the 2 wires.
Reverse the probes and check again.
You should get continuity one way and not the other.