Sorry I missed this thread & your question Sue. I may have mentioned before on an earlier thread but an OEM fan clutch with the original fan blade fixed my over heating issues. My engine temp acted exactly like yours until last April when I picked up an OEM fan clutch. I was cranking the A/C on Cliff Hanger while you were on Top of The World and my temp never moved from the normal operating temp.
I previously tried several aftermarket fan clutches, electric fan, & the coolant temp sensor Wintermute mentioned (agree it's very easy & cheap to replace).
My suggestion... try running your new OEM fan clutch with the original fan blades. You should be able to hear the fan slighlty more than the engine during accleration -at least that's how my setup sounds.