It could be a few problems. Thermostat, fan(s), thermoswitch, radiator, etc.

Try flushing your coolant. Sediment in the radiator may be causing a blockage. You also may need to replace your thermostat. Your thermoswitch may also not be working. When you're sitting at idle and the car starts to overheat, is your A/C button pressed?

Lastly, driving the car in the shape that it is in is not recommended. With a lack of proper cooling, you're putting increased stress on the engine and internal components due to the increased temperature/friction. The reason why the temperature goes back down when you move is because you have airflow circulation. This is serving to cool the engine off. When you are stationary, there is no airflow.

My best recommendation is to park this car until you find the problem.