My 2006 Toyota Sequoia's engine runs hot when stopped in traffic. The a/c also get warm. Does fine on highway, though. What could this be?

What is your question?

By stopped in traffic, I mean in town at traffic lights. The engine coolant will come out on pavement. As long as we are on the highway, it seems fine. We have had the truck since new, and it has 259,000 miles on it. We have never had trouble with the vehicle. I thought at first it was just age, but wondering now if it is the thermostat.

What makes this problem better or worse?

Idling with a/c on.

How long has your 2006 Toyota Sequoia had this problem?

Did this last year, too.