Eagle Talon: CPU weirdness and resetting?

Try to make this short and to the point. Many details leading up to this but want you to know what I have dealt with. Mainly the CPU seems to reset while driving which cuts off the car and sometimes I can pop the clutch and restart and sometimes not. I was under the belief it's either overheating or CPU is going bad or power supply is bad. I did a total cooling system job including new thermostat, heavy flush, and refill. Runs cooler for sure. I can wipe heating issue out. Car still does the same at random whether driving car hard or not much at all. Not cooling.

It seems when I have it cut out that if I clean the posts and terminals with tool it doesn't do for awhile but I do notice corrosive build up happens pretty fast on the terminals but cleaning always seems to make it longer until the next cut off.

One thing that stands out is I have a rear O2 sensor that had wires severed and shows as a 1-2 fault code on dash. When check engine light is on car never dies but when it cuts out I notice the check engine light is off. That's how I can tell it's resetting or shutting off (CPU).

Doing more tests I realize that even if I leave battery diconnected for a very long time and hook back up and run car that when I kill it and check fault codes it will always have 1-2 O2 sensor prob but not showing the check engine light. Usually comes on after 15-20 minutes driving.

So my question is why does the car only run great when check engine light is on and why would it give me the correct fault code after reset and running but NOT give me the check engine light although it knows the problem even after the battery reset?