90 300zx n/a won't shut down

[4x4_Welder]

Hey, I have a problem here to challenge the best technical knowledge. A friend picked up a car that needed a key switch, supposedly. It won't shut off. Well, about 30seconds of diagnostic time and I found the key switch was fine, power shuts off there when the key is turned off. All the gauges turn off, and even the idle speed control shuts off, but the engine stays running. After manually stalling the engine, the EGI and ignition coils relays are still engaged. Pulling the EGI relay shuts down both, but the power is back on when I plug it back in. The relays stay de-energized if the battery is disconnected and reconnected.
Checks so far:
Disconnected alternator, no change.
Disconnected all aftermarket stereo equipment, no change.
Pulled fuses and relays for all non-engine related stuff, no change except the wipers came on briefly when the key is first turned on.
The battery light doesn't operate at any time. It has power on both sides of the socket, and the bulb is good. This makes me wonder if it's charging system related, but disconnecting the alternator didn't do anything.
I opened up the computer compartment, and there was some sign of water intrusion a while back, no current dampness, and while the computer case had a nice dent in it there was no sign of internal parts contact or water inside.
Has anyone seen an issue like this before?

[jbracy7]

Devil z,man u will be chasing that gremlin a while

[4x4_Welder]

Hope not, I'd rather be working on my diesel swap stuff but the car needs to behave.