Cooling system was flushed, heater core is not blocked, blend door works. One heater hose is hot the other heater hose is cold.

I installed a home made T bleeder on the cold outlet hose.

What would happen is I would get coolant flowing through it, then it would stop. Some time would pass and same thing would occur. There’s some bubbling in the reservoir bottle as well.

Otherwise trucks runs great stays at normal operating temperature. Can someone troubleshoot with me what the problem might be?

 

Sounds like you need to finish purging the system of air.