[doobiess]

nope changing the temp. rating on a thermostat wont do anything but do more harm.. since the computer is set to run at that temp so if its always open and temp dont work then it will run more rich and so on.. always use the oem spec unless the ecm is modified..

Next make sure your overflow tank cap is good or just buy a new one... next im betting you have alot of air in the system.. use the bleeder screw to remove ALL! the air out if you dont know you get air pockets and then hot spots form and then the water pump wont work right and sensor gets false readings and so on.
The bleeder screw is located on top of where the water pump .. make sure the air is out and you have the heat on full while doing this