I had my timing belt, thermostat, water pump replaced last Aug. 2002. I got called up for OEF (Op Enduring Freedom) so I left my 4Runner in AZ with my Dad. I came back last week (good to be home) and drove back to CA and the temp gauge went all the way to the right (hot hot hot). I had to turn off the a/c and run the heater full blast (outside temp was about 107). Anyway when I got near San Diego I turned the heater off and the temp stayed in the middle but went up when I climb the mountains. I searched the forum for some answers and I read that I have to let the truck "burp." What other actions can I take to solve this problem?