1996 Honda Ballade oveerheating

I have replace the head gasket, got new thermostat, new radiator. The temperature goes up when in hot weather and when I have to put pressure on the system. In most cases it reaches the red red, then we have to slow down and it will eventually go down again. When i'm in traffic the temperature goes sky high again and then I have to drive a bit faster to get the temperatur down. In most cases when in traffic I can't do this and have to switch the car off. When the car is runniing for almost an hour and the temperature goes up, I slow down but don't switch the car off and then I check if the fan is running, but the fan is not running. There is no leaks. Could it be that I need to replace the fan or the clutch fan or could be the fan blade ro maybe the new fuel filter is clogged. Please help