I keep having overheating problems with my 88.

I keep having overheating problems with my 88 rx7. So heres what I found out. It started when a water hose on the back of the throttle body broke. I had that replaced and then water started to leak from the radiator cap so I replaced that thinking thats why it was overheating. But it kept on overheating still. I looked around and found that the thermo valve on the throttle body was clogged and while trying to take it out I broke something on the housing. I didnt changed the valve or housing because someone told me I could just make the hose straight and forget about the valve and housing. After I did that the car was fine whenever I started it up it would say add coolant but once I started driving it would go away. But now it overheats again and air is coming out from the radiator cap instead of water but water does come out but also air. What coudl eb the problem