overheating when it is sitting idling goes back down when you are moving

Hello, have you checked to see if your cooling fans are turning on? When idling at a stop, the cooling fans are what forces air through the radiator to cool then coolant -- which is essential! When you're moving, air flow does it. If cooling fans do not turn on when hot, or when you turn the air conditioning system on, then it's a great place to start troubleshooting to find out why. www.repairpal.com/repair-shops