I have a 1999 4.3gs, probably wired same as yours so I can check some voltages at certain areas if you have specific requests.
Question: what happened just prior to this issue? Did you try and jump start? Did you install some new electronic device?
Did you check all fuses? You said you direct wired fuel pump so when you allow key to go from start to run does the pump stay running? All wires tight and not corroded on alternator and distributor?
Did you try to direct wire coil with on/off switch just to see if it stays running?
Did you check your low oil sensor if your engine has one it might be stuck open and not closing to allow current to flow through... Just throwing random thoughts out.
If you disconnect your kill lanyard does the engine still start in crank position?