A question, does it run hot all the time e.g. idling and highway running. If it just runs hot at highway speeds it could be a partially clogged radiator. If you can get to all the parts of the radiator see if you have any spots that are a geat deal hotter than the rest of the radiator. Flushing may not always get several clogged tubes. this may not be it given how well you have kept the car. Just an idea! You may not have an aluminum radiator but if I'm mistaken it has an all aluminum engine.
99 Harley Davidson Ultra Classic
97 Dodge Ram
auto\hydraulic mechanic 20 yrs