Please help once again....

About 3 to 4 weeks ago, I posted my 740T overheated, blew trhe radiator and started running on what seemed to be two cylinders. What I have done since is replace the radiator with a new one, all the hoses, thermastat, plugs, wires, cap, rotor, coolant tank, cap, and air cleaner. The car runs fantastic!!! The pick up is awesome and the car is a lot quicker than it was.....But it still overheats, like a siv. I've checked the timing and the belt and it's fine, The converter is clear, I'm at a loss. I loose coolant but not by dripping, and no white smoke through the exhaust, not in the oil...... What do I check next? Signs of a cracked head??

Rick Plett