Imo you have some sort of blockage within the cooling system, wether the thermostat is jammed shut or the radiator is blocked as a couple of examples. I had a 2.8i Capri that done this many moons ago now, was getting hot, building pressure in the cooling system and spitting the water out of the heading tank after driving.

I immediately thought head gasket but fortunately it was the radiator that was blocked which was a much easier and quicker fix not to mention cheaper. I would flush your cooling system and check everything is as it should be, stat, pipes etc and go from there.