The engine temp when warmed up shouldn't be lower than the thermostat temp which is ~180F. The AMS was not what solved your problem it simply put a band-aid on it.
It will be 30*-100*F here in the and my engine temp is a steady 180*-190*F. Unless the A/C is on and I am climbing hills then it get up to 210ish. I am running the stock system 50/50 water/antifreeze + water wetter.