94 Chevy C2500 temp guage won't work

I can't get my temp guage to work in my truck. I've changed the temp sensor and changed the thermostat and checked all wiring for good connections and everything seems to be ok. I'm probably answering my own question but could the guage just be shot? The previous owne said he did have a problem with the guage fluctuating. He said it never overheated but it would get a little on the high side then drop right back down.