Series 60 DD-Erratic Water Temp Gauge HELP!

This has been going on for awhile now...but my water temp gauge in my 97 Freightliner FLD day cab (12.7L) will intermittently wag around and show weird readings. Some days it works flawless, some days it does it all day. I got a video of it I'll post in a second, but it will wag around and if the needle spikes into the red, the CEL, shut down, & high temp warning lights and buzzers all come on for like 5 seconds, then go out. And the engine derates when that happens. I've replaced the low level coolant sensor, water temp sender (passenger side just under head), and the water temp gauge pod itself. It seems like it does it more when I'm fully loaded vs. empty. But it's done it when I'm empty. Tried chasing wires, couldn't find any obvious issues...Could it be the ECM itself? Truck has about 840k miles on it with no rebuild yet. Front head gasket leaks on the passenger side, barely. Bars leak has fixed that. I'm hopefully going to be stepping up to a newer to me truck at the end of the year. So not going to dump any money into this, but would just like to fix this issue as it is very annoying trying to climb grades with loads while the water gauge wigs oit my truck will get derated shortly...Any ideas? Video will be up soon

Thanks

 

Here's the video of what it will do...it didn't spike into the red in the video, but that's what the gauge does...very annoying

http://www.youtube.com/watch?v=XYO4aRHdGDA&feature=youtu.be

 

Where is that/the wires located??

I feel like it's not a wire issue though, because more times than not, if I work all day, the 2nd half of the day it usually works flawless....almost like it's "warmed up"...

 

Can I see wires or do I need to unbolt housing etc?

 

Thank you. I'll check it out ASAP!