If the outlet hose is cold, the problem is in your heater core. Have you tried flushing again to be sure there is no air pocket in the system? You have pretty much isolated the problem, now to figure out if it is air pocket or clog in heater core.

http://www.publicsurplus.com/...owse/cataucs?catid=4 <<< Click on link and see our surplus vehicles for sale.
Being way2old is why I need help from younger minds.