New thermostat. New water pump. New radiator. Bled system. Mishimoto Fan Switch.
OEM thermostat(78C). Directly from the dealership.Is the thermostat OEM? Does it get up to temp from cold normally? the thermostat is the only thing that will restrict flow to prevent the coolant temperature from dropping too low.
It is a slow mechanical item though, so sudden high RPMS or low load high RPM situations can make most gauges drop before the thermostat closes and restricts flow
Is the the thermostat installed backwards?
I asked because if its not returning closed correctly it will take a much longer time to warm, and will cause the temp gauge to drop if it doesn't close up when temps dropAs for warming up normally, it does I guess. The upper hose gets hot as well as the lower hose.