I recently purchased a 1999 Audi A4 Quattro. It has the 2.8L motor in it. The car runs great, but I have noticed while waiting for my daughter to get out of school, it runs hot, I usually switch the car off when it gets up past the notch after half way. Also, the AC goes from cold to not so cold when idling. The car has 140k miles on it and I really have no idea what past maintenance has been done to the car unfortunately. I have a new water pump, timing belt and thermostat. My bf is a mechanic and will be changing these, but could the overheating problem be something else?

Thanks!