Intermittently will not turn off with the ignition switch

Hello, because of the vehicles age, it's very difficult to find the correct wiring diagrams. Is it Fuse #14 you have to pull? It sounds like you have a relay that has some carbon build up on the contacts and is keeping a circuit to the ECM active. Can you pull the Main Relay here in the diagram below and see if it will stop the engine? Also, when the issue does happen before you pull any fuses or do anything else. You should see which pin on the ECM is still receiving 12volts. If it's (in green) this ECM Pin A6 black/white wire, then you would know it's this main relay keeping its contacts active. Again, we have very limited wiring diagrams, so any fuse number that you're pulling, or additional info would help. But a relay staying on is really the only thing I can see to keep the engine running. Unless there's a circuit inside the ECM that has a corroded and causing contact. But checking any connectors for corrosion would help too.
Is this problem running the battery down overnight as well?

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

https://www.2carpros.com/articles/how-to-check-wiring

If you have the vehicle running and can't shut it off, you can check for power at these two locations with a test light (in yellow), that will tell you the relays still powered up. The other control wire for the relay that says "Hot in Run or Start" should not have power when the ignition switch is off. Is there a number for the Ignition Fuse?

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit