1999 Dodge durango Heating issue

[shrhuston]

I have a 1999 Dodge Durango that we just pulled a 318 out of and put in a 360. Running good, the only issue I have now is that the heater is not blowing hot. The heater core inlet hose is hot but the outlet is cool. I installed a new radiator with the motor swap and I have flushed the heater core out good. When flushing I alternated the water in hose from inlet to outlet several times and used a chemical flush as well. Good out from both directions. I primed the heater core with coolant before reconnecting the hoses, still no heat.

When I took off the heater core inlet hose there is just a trickle coming out of it while running.?

Couple of Thought:
1) Can the heater blend door be stuck open pulling outside air (40s here now) be a cause?
2) Has anyone re-routed the outlet hose to the hose going into the thermostat and plugged the line coming from the water pump?
3) Any other suggestions?

Thank you
Shawn