My car's temperature also rises slightly in stop and go traffic. Check to make sure that your aux. fan is working and coming on when necessary. Also, as a quick fix in a desperate situation, turn on the heat in your car (and turn down the windows of course). By running the coolant through the heater, it helps to cool the engine's temperature, you'll notice the temperature go down to a more comfortable level if only temporarily.
1976 230.4 W115