Thermostat Malfunction?

[JAXX5]

So while chasing down an erratic engine temp issue, I arrived here. It all started with an upper radiator failure. Got stranded, nursed it home with gallons of distilled water bought from a nearby Walmart. Got home replaced hose, then on way to work next morning engine temp went to 3/4 on gauge, stayed then dropped to normal like a rock. On the ride home that evening, engine temp stayed normal for a bit, then rose to just over 3/4 on gauge and stayed there. I nursed it home and parked it... this is what I found today. The t_stat on the left of course is the one I removed from my "X". Has to be changed, yes I know, but you think this would cause my erratic engine temps?