91 Legend Overheating

Hi, I have a 1991 Acura Legend and i have replaced the water pump, timing belt, thermostat and both the head gaskets as well as the radiator. The car overheats while bleeding which is odd. I fill the overflow to the max line and remove the radiator cap and fill the radiator up with the bleeder screw open. I then close the bleeder and proceed to let the car run. Note i am using a spill free funnel. After about 5-8 minutes the temp rises and the upper radiator and rad hose gets really hot so im assuming its the thermostat because the upper hose is hot and lower is cold. So i shut the car off and let it cool off, about 2-3 minutes i hear the fans kick in and i touch the lower hose and its hot. So im assuming the thermostat opened, so i start the car back up and the lower hose goes cold which is odd and the upper gets hot again. Im stuck, i dont know whats faulty or not and i cant keep on letting it run because it will overheat even with the rad cap off. Any suggestions or procedures to follow would be greatly appreciated! I know Eric’s expertise in hondas and legends in general through his videos. Thanks in advance .