Toyota Repair: Toyota P/u heater, radiator shops, heater control valve

Question
Toyota P/U, 4x4. Heater blows cold. I've removed and inspected the heater control valve and back flushed the heater core. The temperature gauge shows normal operating temps. I've even tried blocking the radiator on very cold days to increase the operating temperature. I've made sure that the slide controls do actuate the valve. Still blows cold and at best, slightly warm. When I backflushed the core, there seemed to be good flow. Is it possible that I need to 'burp' the system? could there be an air pocket? The intake hose going to the core runs hotter than the return hose. Any help?

Answer
The heater core may still be partially restricted, even though it shows flow in and out, if the heater core is blocked except for the area next to the in and out pipes no water would circulate through the rest of the core but still show a lot of flow of water, most radiator shops can open the core ,clean it and solder it back together, I would recommend doing that next.