I would double check connections before investing in new gauges, sounds like bad wiring.
As far as the temp sending unit, they are pretty flimsy and can break pretty easily when installing, double check that. I am assuming that you changed the right one, the one at the rear of the head on drivers side...4 cyl.
2013 WRANGLER SPORT 2 DR., V-6 ,AUTO,HARD TOP
)1994 Jeep Wrangler 2.5L, Bestop top
/w steel half door and slider windows
5 speed, 2.5" lift, 31" tires,rack lights