Heater warm air not hot?

Heater not producing good heat. Checked the following: radiator full and reservoir, air intake clean and clear, temp gauge shows temp in middle of C and H, it is blowing warm air but not hot, heater hose at firewall register 151 and 143. dealership changed out antifreeze last year. could there possibly be too much antifreeze and not enough H2O? or should i check heater door actuator?

Suggestions?

 

How old is the Tacoma? I would first check and make sure the door actuator has full movement as you suggested. If the door has full movement I would suggest cleaning out the inside of the heater core. Older vehicles can have material build up inside the heater core which prevent good heat transfer. Reverse flush the core by removing both heater hoses and running hot water through then compressed air. Repeat this about about 10 times.