I Have A 95 Subaru Outback overheating i replaced thermostat and did a coolant flush put a flush tee in the heater hose filled with coolant and it still overheats the top hose gets hot but the bottom hose stays cold and it boils over out of the over flow any suggestions i do have heat blowing out of the vents then sometimes when it overheats the air gets cold and some times it stays hot

It sounds like you still may have an "air lock" in the system.
Some subaru radiators have a bleeder on the top of the radiatorinlet tank oposite the cap. It has a cross in the top that will accept a flat svrewdriver this will allow you to "burp" the system and to fill it to the top.

Check your radiator cap, they are cheap and easy to replace.