I have a 1999 Toyota 4runner limited with 145,000 miles. I get very little heat from the heater, it does better on Recirc, but barely works on exterior air. I've had the Heater core and thermostat re

I have a 1999 Toyota 4runner Limited with 145,000 miles. I get very little heat
from the heater, even though the engine temp gauge comes up to
temperature nicely. The heat does better on recirculate, but it barely works
on exterior air.  I've had the Heater core and thermostat replaced, and the
coolant level checked and double checked. Still not much heat, Any
suggestions as to what I might do next?

My local Toyota dealership has quoted me $668.00  for a heater repair cable,
248.38 for a water control valve and $3028.00 a head gasket replacement.
This seems crazy, the motor oil looks fine so I doubt  I need a new Head
gasket and I don't see how the head casket would effect interior heat....