[clubracergt1]

That sucks, dude. Very good chance that there is/was air trapped in the cooling system. Ford has a wonderful habit of not making the pressure cap the highest point in the cooling system. That's why you sometimes will see wierd threaded plugs in the crossover tubes. Also, the only thing that the hole in the t/stat is for is to allow air to get out of the cooling system. No hole or a smaller hole shouldn't cause any problems in operation; but it will be hard as Hell to get all the air out of the cooling system. The easiest way that I know of to get the air out is to run the engine up to operating temperature with the radiator cap on it, allow it to cool, remove the cap and refill. Try this a time or two, and it will likely help out. We have problems with air whenever we flush the coolant on many of the newer cars, and this seems to be the easiest way to get it out. The air will eventually find its way into the expansion tank. Eventually.