What I may do is drain refill and add flush/ cleaner . flush again,

then pull radiator and fill it will cleaner only and let it sit a while.
the flush it seperately.
resinstall and go for a drive

Right now, car has 1 gallon coolant, then filled with tap water. new 160 Stewart Components stat . No water wetter of any kind
And if I were a betting man would say its over 200 degrees. ( I will know tomorrow afternoon ) And I know some say thats not hot
But its to hot for my tastes