maybe the clutch
Need to change your thermastat i have done that but still over heats when driving
(Charging System , AC , Power Steering)Fails Continued driving will cause Engine to Overheat . Risk of Serious Damage !
Yes, low coolant will cause it to overheat without the AC; that is not the only reason that will cause overheating however.
Check the transmission fluid level.
Usually car that only overheat in traffic have a radiator fan that does not work. It will not over heat while driving because their is enough air flow.
It could be a bad fan clutch. If the fan clutch goes bad it could cause it to overheat while idling, but it would cool off when driving due to the wind going over the radiator.
Bad water pump, stuck thermostat, clogged radiator, blown head gasket, trapped air in cooling system, defective cooling fan, defective thermal relay, or a combination of these.
Died while driving? Alternator
fuel pump relay may need replacing
The gas mileage for the 2009 Toyota Tundra depends on whether you are driving in the city or on the highway. In city driving will get you 15mpg while Highway driving will get you 19mpg.