Follow the ground from the battery to the engine block, firewall, body at rad support and inner fender(*).

What model?

Ah, I missed the wires being replaced. Cool.

Is this the temperature shown on a reader or is this the temperature shown on the dash?

Temperature is shown digitally and on dash.

Does running the A/C affect it? In moderate temperatures this would keep the fans running and hopefully keep temps right up against the thermostat in moderate temperatures.

I am thinking exhaust restriction, like a plugged catalytic converter.

AC is always on in the summer time and both fans are working properly. As for the catalytic converter there are no signs of restrictions in fact there
is an exhaust leak at the beginning of the catalyst converter. Im not sure if i mentioned it earlier but i dont get any codes coming up when this
problem happens.

What brand was the MAF? I ask this question because a cheap Chinese Mass Airflow sensor can wreak havoc with your Air/fuel ratios (fuel trims) and thus cause drive-ability problems.

MAS was from Standard Motor Products

oops.....MAF sensor

I have a 2000 Park Avenue and ran into a missing problem last Summer and had a lot of trouble figuring it out. I kept getting a miss on cylinder 6. Had about 188k miles with original wires and plugs. Changed those and still had the miss on 6. Changed the coil packs, still had the miss. Changed fuel injector on 6, still had the miss. Then I went to the wires that originally came with the car which I think were Delphi but whatever came with it and that did the trick. I had brand new lesser name wires and they weren't getting it done. I can't get over how many cruddy parts exist out there. You have to go with brand name stuff. I realize this is different from your problem but in the ballpark. Also, my Park Avenue runs at about 205 when idling pulling over until fans kick in so I'm not sure the temperature is a factor in being too high but that whatever is the problem is getting exacerbated at a higher temperature. So we have to think what that could possibly be that is not throwing a code.

So if its not the cat and a somewhat clogged exhaust, it could be the MAF.

Back in 2012, I would start the engine and it would stall but I could start it back up while giving it throttle. I thought Idle air control but that didn't do it. I then replaced the MAF and that did it. On my 1985 Camaro back in 2000, I would hit the throttle hard up a hill and get a total power shut off, like a governor or a spark retard came on. It was not fuel delivery, not the main engine computer, not the ignition module. It was the MAF. So when these are going, they can demonstrate different ways of affecting engine running,
I would test the MAF, maybe unplug it and see if the engine runs better when it demonstrates the stall but of course there is a more scientific way to test which I haven' done. Hope this post offers some clues.