Fuel Gauge

My fuel pump went bad on me about 8 months ago, put in new in and ran great until now. The fuel gauge is bouncing and not giving me a good reading. From example I fill up uesterday and when I turned the car on it went to empty and then worked it way back to full. But a little while after that I stop at a stop light and it went to 1/4 and then back to full. This happened when I was moving from Wyoming to Texas (1000 miles). Every mechanic has told me that me fuel pump and sending need to be replaced. So I went ahead and replace it again and it still is not reading right. I replaced the wiring harness to both the fuel pump and sending unit. Along with the relay fuse and any other fuses that has to do with the fuel. I am at a lost here.