My memory is questioning if this car was equipped with the expansion tank and re-reading the original post he says he does NOT have the tank. In my Mustang we wouldn't fill to the top the radiator to allow for expansion. Also, if it burped any after shutdown, I didn't worry about it, it was normal when it was really hot out. If you'd like to. You could add an expansion tank and get the proper cap to allow it's use. It helps to keep the radiator full!

I'd question if your radiator core isn't slightly plugged up. But, 110 ambient is certainly not going to help cool that car! When was it last flushed out? (The radiator) maybe it has never been serviced and now it's just not as efficient!?!?! Also adding a shroud is certainly cheap insurance to ensure optimal airflow THROUGH the radiator.. hth..