Have you tried driving on the highway at a steady rate of speed? If there's an issue with the cooling fans, it should operate at normal temps on the highway. If that's the case, just replace both fan motors because they are likely both original, and not strong enough anymore. I would also suggest finding a way to check the actual temp of the cooling system (without removing the cap!) which should average 200-220F when the gauge is steady warm. I use an infrared thermometer and check the radiator, and where the coolant is flowing in or out of the engine. You can also perform a cooling system flush, replace the thermostat, and ensure that the coolant mixture is no more than 50%. Honestly, If it's not something clear or obvious, you can lose a lot of money throwing parts at a problem. I would take it to the dealer because most service centers have a standard diagnostic charge which is normally around $100.