An oil temp question...

THE BULL

Gauge is staying lit upon shut down.

I would start the diag from here, Oil temperatures should not changing that drastically.
One cheap way to test is to get it to happen again, once it does plug in your OBD scanner and see if the ECM is registering the same temperatures.
If it is then it point's towards a bad sensor or faulty wiring to the sensor.
This technically should throw a code but possibly not since temp's are within specs.

Secondly the Triple meter is fed by 5 wires.

Batt
Acc
Ground
Cluster CAN H
Cluster CAN L

Let's assume ground is good, this would leave the issue between battery feed and accessory feed. It's possible that you have a faulty power feed to either of these two pins. Sometimes a loose triple meter connection, though triple meter failure is rare, if you've confirmed that ECM reading is not the same as the Triple and power checks out you should try another Triple and see if the issue goes away.

Good luck