My 2000 V6 Temp Gauge showing Hot

I noticed about 6 months ago I had just started the truck and looked down and notice the gauge pegged hot I quickly stopped the truck and turned the engine off popped the hood and it was not hot at all got in the truck started it up and tapped the dash above the gauge and the needle went to normal. over the next 6 months it had been doing this and I would just tap the dash and it would go to normal. Now as soon as I start the truck it always pegged hot. I recently had the radiator and hoses replaced so I know I am not actually overheating but it is a bit unnerving to see your gauge pegged hot. My brother said its grounding out need help with locating this ground and how to fix this any help would be great thanks

 

Need help where can I look to find this problem now when I start the engine anytime it goes right to hot has anybody experienced this problem

 

did you ever figure out your issue?