(2010 40th Anniversary) Changed spark plugs and cleaned throttle bodies and now heat works for ~15 minutes then goes cold. Will blow "hot" if I crank the temp dial up, but temperature not consistent at all (gets warm then cold then warm...). Fan speed and selector controls work fine. Oil temp and water temp in correct range when it happens and not an issue. Coolant is filled to reservoir max line.
- Thought it might be the thermostat so changed that...not fixed.
- Thought it might be air in the heater coolant lines so drained and flushed three times with super slow fill and front end jacked up, revved out bubbles...not fixed.
- Though I might have knocked a connection loose behind controls (new radio install) so disassembled and triple-checked all...not fixed.
I'm out of ideas and about ready to head to the dealership. Does anyone have suggestions on what else I could do first?