well if coolant leaks into the combuston camber at 13psi imagine whats going on when the air/fuel is being ignited at (180psi),
also having no shroud will cause it warm up alot because the fan isnt sucking air from the radiator, its just sucking it from the engine bay
just try put the shroud back on go for a drive and see if theres a improvement
also try giving the fins on the radiator with a high pressure spray from the car wash just incase its blocked