I'm still thinking the NGK plugs are sparking at a more optimal time with a higher intensity spark. Which gives a more complete burn and allows the combustion to escape through the exhaust valve at the right time.

The Bosch plugs seem to have a bit of latency in their sparking. With the engine rpm at 3,000 just a tiny bit of latency could throw off the combustion cycle. The ECU it telling the spark plug to spark at a certain time and if there is a tiny lag in that spark time, less burn would occur before the exhaust valve opens, trapping some of the yet combusted fuel in the cylinder. Not a whole lot, but enough to make the engine run just a bit warmer.

The car does feel like the engine is running smoother....call it placebo, but as I have said this is my DD, it's the only vehicle I have owned since 2013. So I believe I can tell the difference.

honestly.....
re-read your post. I defy you to do so with a straight face. This is one of the most bizarre, misguided ideas I've seen on this particular forum.

I'm somewhat confused by some of your terminology, so I'd need to clarify your meaning, before I begin to tear it apart.
For instance:
"....less burn would occur before the exhaust valve opens, trapping some of the yet combusted fuel in the cylinder."
by this, do you mean "...yet TO BE combusted..."? Is that what you're talking about? And if yes, then how, in the name of Pete, does it get "trapped in the cylinder" when the exhaust valve is open? And, HOW, also in Pete's name, does UNSPENT FUEL IN THE CYLINDER cause more heat? And if I've got ya wrong, and you mean SPENT fuel (we call that exhaust around these parts), same questions apply.

How about we set that aside for a moment. Let's try this one:
"...The Bosch plugs seem to have a bit of latency in their sparking." According to WHO? Do you have the spark-curves for the two plugs, to compare? Or are you suggesting that, because this is your DD, you can FEEL the "latency" in a park plug? Because you're basing your entire hypothesis (I use that term loosely) on this one factor. So there really should be something behind it given how vehemently you've defended it.

But really, this one just takes the cake, for me: "... are sparking at a more optimal time with a higher intensity spark. Which gives a more complete burn and allows the combustion to escape through the exhaust valve at the right time."

this is just.... i dunno.... um.... garbage?
Are you suggesting that the "timing" or "intensity" of the spark has anything whatsoever to do with when the exhaust valve opens, in relation to the exhaust stroke of the piston? Because if you're NOT suggesting that, then this statement is just plain fanciful misunderstanding of the basics of 4-stroke engines. And if you ARE suggesting that, well then, that's ALSO just fanciful misunderstanding of the basics of 4-stroke engines.

Now, it's possible that what you MEANT to say, is that a more complete burn would allow more...... nope.... see? I can't even think of what you could've meant that would be any less ludicrous than what you wrote.

Spark plugs
 

I’ve ran these 4 prong plugs in another car of mine. Not sure but I definitely noticed it ran hotter with them. I don’t care what anybody says it ran hotter. No doubt about it. So changing from a 4 prong plug to a single I believe it can make in run cooler. I don’t know why but I’ve seen it personally and it’s true. If I didn’t see it personally I probably would think much of it myself.

No, it is not. As described earlier in this thread, changing plug heat range or design DOES NOT change the cylinder temperatures. Heat range is only describing the RATE at which heat flows away from the tip of the plug after it fires, and these differences in flow rate are changes at the millisecond level, important to how clean the plug tip stays, but again make no difference in the amount of total combustion chamber heat generated. Plug tip design (single vs. multiple electrodes) is totally irrelevant to combustion chamber temperatures as well, and is only important to the plug's life expectancy (how often it needs to be changed).

If you changed plug type, and then saw lower operating coolant temperatures, you saw a coincidence, not a cause and effect.