why my 1996 acura tl 3.2l temperature gauges goes up to hot then fall down? on 1996 Acura TL

Changed sensor and radiator

Asked by for the 1996 Acura TL
When the guage drops to cold are you still getting heat inside? is it randomly going up & down quickly or is it gradual? the guage may be faulty or there may be air trapped in the system . when you changed the rad. & sensor , did you change the thermostat? Is it functioning properly.