If the engine is just cutting off, I tend to agree with you. It may well be electrical. When you pulled your radiator cap off, and your thermostat opened up, did you witness a lot of water movement through the opening? If little, I would say the pump is gone. This may well be a combination problem, where the actual problem is affecting the ECU to cut off everything to protect the engine.
Check out "YJ V6 Conversion" if you want to see a frame up restoration of my 1992 YJ.
Check out "WWII Jeep Photos AND Restoration of..." if you want to see the original JEEP in action...