okay so ill just get to story with all the facts, after my water pump blew and got it replaced i have been overheating. at 1st it would start to boil over after about 15 20 min and the temp gauge would go up then go down as i was driving but never going back below 3/5 - 1/2. i got the thermostat replaced with oem and changed a leaking rad cap, now it takes 30 - 40 mins to overheat. the car has been bleed manly times. for as far as i have tested it is fine during idle, only when driven does it overheat (and i dont drive like an idiot shift early ease down on gas). i was told my coolant seals maybe gone is there a test i can do to confirm this?

 

This should help you:

http://www.aaroncake.net/RX-7/overheat.htm

Basically test for bubbles in the radiator cap, and have the cooling system pressurized. You can usually rent the pressure tester at a parts store.