First thing two things to check whenever a generator shuts itself off are oil level and the possibility of overload. My guess (and that is all it is) is that it is not oil level because it runs for for 4 hours, but I'd check the oil level just for giggles. At worst, if the oil is a wee bit low, adding some is cheap.
The overload possibility however, is likely. The ACs are going to draw easily 6,000 watts if they all start up (coincidentally) at the same instant. Could it be that the microwave was running (another 1100 watts) along with the water pump and some lights and the coffee pot, and . . . which would get you 10,000 watts?
The fact that it runs fine for 4 hours, then quits, suggests to me an overload condition, more than anything. But then I am not an expert on this particular generator.