3.4L Temp Gauge Erratic and Truck Stalling

2001 3.4L V6 with temp gauge acting erratic with stalling. The truck will cold start normally and ultra gauge reads 185, as soon as i leave the driveway the temp gauge on the dash will fluctuate and shoot to the top.. the truck will then stutter and stall and then won't restart, it will just crank without a spark. The ultragauge still reads 185-190 degrees then the ultragauge will shut off for some reason.

No CEL, changed my thermostat and still does it, coolant and oil level looks good. i am stuck! Bad ground?

 

Just my thought or something to check, MAYBE not sure - electrical gremlins how's your battery, alternator and grounds. My truck did crazy stuff when my alternator was going out.

 

IMO/experiences
Any gauge that “pegs”

is a ground issue

 

I checked all my grounds and everything looks solid! I actually drove the truck around for 20 min today, it ran great. started right up on a cold start but and temps remained 185. Pulled back into my driveway after 20 min and the gauge shot up and it started shaking and stalled. im so confused haha