overheat

You said the temperature gauge gets up to the over heat region of the temperature gauge. Does the car actually over heat/ boil over and or loose coolant? When the temperature gauge starts to climb into the hot area of the gauge pull over and lift the hood, do you see and hear the electrical cooling fan running? Are you having to frequently top up the coolant expansion tank or radiator? You say you shut off the car and things are OK. How long are you shutting the car off for. I will send you an article I wrote for Rpairpal that we have not yet published I hope it helps