I bought this car about a month ago. Had a power steering leak and a coolant leak. Power steering leak stopped by its self with the thanks of fluid with stop leak in it. I changed the thermostat housing as that's where the leak was coming from. That stopped the leak. After sittings still for about 10-15 minutes the car will start to overheat. But once I get going it cools its self down. New water pump to any ideas?