Not a hose. Recheck the heater core hoses & if one is hot & one is cool then the core could have stopped up again.(may need to reflush) Also check the blend door. I also had a truck that came into my shop for the same thing as the engine would get hot & cold, The heater would only get hot when the guage on the dash showed hot & when it went fluctuated back cooler the heater was cold. (end result) Small head gasket leak.But of course he was also loosing coolant over time of a couple of days.
