Tru

Has anyone had problems with their RX300 overheating? Mine is a 2000 less than 100 thousand miles. We are having problems with the car overheating only after we have driven a ways lets say 20 miles or more. We had the waterpump, timing belt, thermostat, radiator temperature sensor (something like that) replaced. No problems that would indicate a blown head gasket. The fan does not coming does anyone have any ideas what could be causing this?