96 Astro with little heat

I have a 96 Astro that blows little heat, I've changed the thermostat, back flushed radiator and lines, checked heater core and the blower is working at all speeds.

You may have the temp flap inside the heater not openning. Are both heater hoses hot going in and out of the heater if they are. Then check the heater temp flap or the vacuum lines on the actuator or the actuator itself. Good luck