I do have a newly rebuilt engine, but this problem existed before I had the engine rebuilt, so I think it must be electrical or fuel system related.

It used to only do this random cutting out/dying after driving it for over 40 mins or so, but here recently it has cut out multiple times in one day, just from getting close to redline, it seems to die/cut out more when "power" button is on.

Just sounds like all of a sudden no fuel and/or air is getting to the engine, it is very sudden and very disheartening. All of a sudden complete loss of power and I put it in neutral and realize that the engine is just spinning and getting no power. So what do you all think ECU or fuel related?