help i tried everything still no heat in 88 ranger 2.9

[wdmgsquare]

I tried everything (i guess) new t stat, new heater core, one of the hoses gets warm but the other stays cold. I switched the hoses and still nothing, i checked behind the control panel the line works the heating core stays cold this been doing this since i replaced a freeze plug (lost all coolant) if there is air in the system how do you remove it. plz help (im pretty good under the hood)