I have very little heat. I need help finding my problem.

What is your question?

I have checked the accurate door, the motor to it. Put in new heater core, thermostat, Flushed engine once. Flushed heater core 2 times both old one and new one. And there is no change in my heat. Also had it to ford dealer. They told me heater core was bad after I had just changed it and went home and flushed it again and all went fine. It is verily warm. Any other Ideas.