i have a feeling there is a partial clog in your radiator. i know its been replaced but this is a vehical that isnt drivin every day. the easiest way to check this is to use a infared temp gun.
they used to be around 300 but have come down alot. you can even get one at your local hobbie shop that sells gas powered rc cars they are now around 50 to 100 dollars.
get one and start it up. when it starts getting hot, use the gun to shoot different spots of the radiator. car off, from the back side of the radiator. 1 side will be cooler then the other. but in the center and areas around it shouldnt vary more then 15 degrees. you may even find a cold spot being 50 + degrees cooler then other areas.
and the heat gun wont be a 1 time use type deal. it can be used for all kinds of things, like checking your bar b que temp, and anything else you can think of temp wise.
hope this helps, let me know if i can assist you further.
I'll hunt for an infared temp gun and give it a try. I'll respond when I accomplish that. In the mean time, thanks for the tip. If it works out, I'll pay the fee.
no problem, let me know how it goes.