How about the air fuel mixture? Lean is hot. Different load on the engine from low speeds to freeway speeds.
Also this ethanol fuel leans the mixture. Run the current gas out or real low if possible and get ethanol free gas and try the same driving.
I have a car that the ethanol free fuel makes a difference on the engine temp. 383 2bbl with A/C complete but not working, so the condenser is there blocking airflow on the 22" radiator. Which means this car is right one edge of overheating or running cool all day.
I second this idea. It's cheaper to do this first and usually easier than changing stuff. At least richen it up with ethanol fuel.
Acting "funky" sure sounds lean to me.
Both of my cars have clutch fans and have driven them in 115° Vegas heat more than once for over an hour at a time in stop and go traffic.
. Yes I have had clutch fans go bad, but it does not effect the temp at speed only idle or low speed.
Good luck with it. BTW I have AC(condenser in front of the radiator and a trans cooler too in front of the radiator) I change the fuel jetting on my 340 when I take it out of town, Mine acts funky too if I leave it jetted lean here at home after having it jetted for 6000'+ out west.
