No heat issues. Need ideas

My truck is not blowing the hottest heat like it use to and im gettin tired of wearing a coat everywhere haha.
-The blower motor works
-ducting is all attached
-both heater core tubes are very warm going into the firewall from the engine bay
-all the linkage is in working condition

Has anyone had this problem? The heater core should be working because the tubes were both hot not just one of them.

First, make sure the temperture control lever is in the hot position. Next be sure it is functioning correctly.
Disconnect both heater hoses, not at the core, at other end of hoses,so as not to risk disturbing the core (causing a leak). Then connect a water hoes to one hose for the core, water should flow through and out the other hose.

Flush the core. It could be partially blocked with sludge or stop leak.

Forgot to add i just did the chemical flush like 4 months ago

You need to do like geterdun suggested and hook up a garden hose up to one or both sides of the heater core and flush it out manually. Adding chemical flushes don't develop enough pressure to backflush the core

Make sure that ALL of the air is purged from the cooling system, tricky on these trucks. Park facing uphill or jack up the front, take off radiator cap, run engine like 20 minutes, adding coolant/water as necessary. Maybe you didn't get all the air out 4 months ago.

And make sure that you use a Stant 192/195F thermostat. Even with a 180F thermostat in Arizona, my B2200 did not put out adequate heat; I made one change, to the 192/195F thermostat.

Hey thanks for the info guys. Ill try bleeding it more thoroughly if that fails then put water in backwards in the heater core with chemicals