This started out with his vehicle overheating with inline or factory 180 thermostat. He said it runs 158 with no thermostat. He also stated that he had new heads, gaskets, pump, radiator, fan clutch.
The suggestions have been, air in system, block needs to be flushed, and we are looking at thermostats as well.
Some of us are not happy with the current factory setup, and do not feel the current inline mod is optimum for these engines, considering the placement of the thermostat(being separated from the block.
i personally do not like 20-30 degree swings in the temp range on an all aluminum engine. While it is true, we kind of hijacked the thread, the intentions are to help the OP and for our own peace of mind.
So feel free to give him pointers to help determine any failure of your said possibilities, i.e. CO2 test, pressure test, etc.