Truck Forums - water temp

hey guys im bryant. new to this site and im hoping yall can help me out. i have a 96 tahoe with a 5.7 v8. recently my truck has been acting weird when driving. my water temp will jump up to warning level, and then immediately drop back down to normal..then periodically it will do it again, then drop back down. i have no idea what i can do to fix this problem. a couple months ago i flushed my radiator, it has a new water pump, alternator and AC. i was told to replace the sensor thats right under the thermostat neck, so i did but didn't fix it..was also told it woudl do this if there was air in the system, so i ran it, then loosened the new temp sensor so that some fluid could come out and then ran it again and it still didn't fix it..any help would be much appreicated! thanks sooo much!!!!