Need Help - Broken stang

Damn last night it was really cold out and my mustang was running damn good, but it was cold so I put on the heater, then all of a sudden cold air was coming out of the vents and my car overheated.

After flushing out the radiator and adding water it seems to be idling fine, but it still is running hot and cold air is still coming out of the heater vents. I havent driven it yet but it seems to idle fine, doesnt seem to be any water in the oil, and no check engine lights. Couldnt see any visible leaks when idling execpt seems like alot of excess water coming out of the pipes.

Anyone have any ideas, Thanks.

Yeah, thats what I was scared of. It is a 94 and it had its head gasket replaced when that recall happened. I guess I will flush the rad one more time make sure the heater core gets filled up then let it run and look for smoke out of the tail pipe, then drain the oil to see if thats where the waters goin.