First when I start the engine it goes from stone cold to fully heated in about 15 seconds the it sits at running temp and never goes back down. The engine temp jumps from a little below half to ¾ and back to below half within the span of about 10 seconds. Once it starts it will keep fluxuating until I shut the engine off, if the temp is above ¾ and I shut it down and restart it IMMEDIATELY the temp will drop to normal and often stay there for the duration of the trip.
I know that your first thought is going to be air bubble, and maybe that’s it but I have tried EVERYTHING I can find about burping and nothing has helped.
This is the method I have used to burp it…
Drive front end on ramps, open filler cap, turn heater to full, start and run engine while reving wait for t-stat to open and bubbles. I never seem to get any air (I did the first time I did this) and I have ran it for over 45min before. If I squeeze the top rad hose it is solid like it is completely full of water.
I have a dual stage t-stat
New rad
New hoses
New temp sender
New cap

It does seem to be leaking a bit of coolant (about 1 cup a week)but It does not drip or anything so I don’t know for sure where.

This is starting to drive me nuts.

*also I am getting light pinging under load (it sometimes seems to correspond with the temp being high)

 

Pinging is gonna happen when temps are high.

I'd check my oil. Make sure you're not getting coolant in there. It has to be going somewhere. No leaks makes me worry about your headgasket. Do some searching for more info on that. It would also change the pressure, thus you get the temp fluctuation.