Gas Gauge Issues

I have a 04 ford ranger it is a v6 3.0 2wd and rear wheel drive. I am having trouble with the gas gauge it sometimes works and other times it does not, I have paid for a smoke test to ensure it was not the fuel pump everything came back normal. I am wondering what else can cause this to not work? I had a toggle switch on there, the shop took out the fuse to this because they thought that was the problem. It is still going up and down sometimes it will stay on empty for days other times it will go up and down, it just depends. I am unsure of what is causing this any advice would be great! I'm thinking it is the floater, but I'm unsure.