Perhaps your fan(s) are intermittent and on their way out?
Did you ever figure out the overheating problem? I have a 1990 Legend V6 that overheats occasionally, only when stuck in slow traffic and not all the time. At idle no problem. Changed thermostat already and flushed system. See no leaks. Fans also come on. TIAPlease let me know if this helps I went through the same thing yesterday. When I pulled over it was smoking so I let it cool off,BUT MY DUMB A S S started messing with the radiator cap and it shot off and anyi freeze flew everywhere(got the burn marks to prove it) I got it towed to the mechanic and he said I need a new radiator cap. We'll see today