2004 2.4L Tacoma Bouncy/Faulty Temp Gauge

As the title states, the temp gauge in my 2004 2.4L Taco likes to dance. Never swings drastically from hot to cold but just sort of starts bouncing with about 10 degrees of play in it. Started about a month ago on a trip to the mountains. Just sitting in the middle and bouncing off and on. Now it's slowly starting to point further north while bouncing, slowly creeping more and more to the red.
Thought maybe the coolant wasn't properly burped after being serviced and the elevation change going from sea level to 6000'+ might be doing it. Wasn't it. Thought maybe the temperature sensor was going out. Replaced it. Wasn't it. Snap in connector going into the temperature sensor wasn't very snappy anymore so I had that replaced. Wasn't it. Pulled out the cluster to make sure the bolts on the back of the gauge itself weren't loose or corroded as I read that was common. Wasn't it.
At this point I'm almost 99% sure that it's just a bad wire somewhere in the line. It can start doing it and I'll pull over, pop the hood, wiggle the cluster of wiring going from the temperature sensor up and it'll stop bouncing and level right back out and be fine for a bit before it starts bouncing again. Or just be driving and hit a bump right and it'll kick off for a bit. Really is very touchy/temperamental like you'd expect a bad connection to be.
Should I just install an after market gauge system at this point? Maybe go ahead and cover my bases and get one that covers everything just in case everything else should start going out as well? She did turn 20 this year. Thanks in advance.

 

I installed an inline upr rad hose temp sensor……..incorrectly

when pwr on Autometer gauge pegged

after some discussions with race friends/forums…..I connected the signal/pwr wires…..but did not have a ground connection

after draining coolant for the 3rd freaking time, ran a ground…..perfect.

I would check ground
Could be gauge….. but my money is on ground (especially bc of the signal when driving over bumps as u stated)
GL
Let everyone know

 

Mine bounces, i traced mine to a pinched wire, it was easier for me to buy a scanguage2 and monitor my temp than it was to unpinch the wire