temp gauge needle jumps

During normal driving. Needle on temp gauge "swings" from mid to over heat. after about 1/2 of normal driving the gauge stabilizes a little over mid. don't know if its the thermostat or what.

first be sure t-stat & fan clutch are GOOD and the system is full and bled [no air]....]is it really running hot or is it a cluster problem]....check the engine first.........then if the gauge still 'bounces' around the most common fault is a loose/missing gauge nut on the back of the cluster.

thanks i'm thinking its a cluster issue now. once i tap on the gauge it seems to go to the mid point.