Heater problem

Hey everyone I'm new to the forum.. But here my problem I am having I know winter is not here yet but for the last couple years my truck 1997 Dodge Ram 1500 v85.2 I have had poor heat in my truck... last year I replaced radiator, water pump,thromstate, heater hoses, heater core, coolant flush and cleaner a couple of times everything in the coolant system is fairly new. When I replaced the heater core I inpected whatever I could see in the heater box blend door and everything seemed good. I bleed the system to get trapped air out. I have no overheat problems temp is always right at 200 degrees I'm at a loss I don't know what else I can do or check to figure out the problem is. Also my a/c works fine so I have no clue what else to do I would appreciate any advice from anybody thank you!