stock temp gauge tweeking out

[mouse2651]

ok so recently i have noticed that in high rpm my temp gauge tweeks and falls all the way to cold then back to normal when i shift. now when i reach 1700 rpm it drops to cold and back to normal when i shift. i figured it was just a wiring problem so i tore apart my gauge area and pulled my cluster to have a look at the wires. everything looked good no scorine or exsposed wires or anything so im in a dalema. im not about to pay a profetional 200 300 bucks for him to tell me it was just two wires touching..( did that dance once before) so what do you all think it could be could it be a little further down the wiring harness so i have to take my dash out? or could it just be a messed up cluster? so thats my question let me know what you think thanks