Fuel filter gauge help please

So I got this fuel filter gauge in the truck I've been driving the last few weeks. Goes from 0-20. Used to read between 2-5. Last night it would go all the way up to 18-19 when rolling down a hill and not giving it any gas. So I changed both fuel filters today, but it didn't seem to help. It will be around 3 at idle, anywhere from 6-9 when my foot is on the gas driving, and goes way up to the top when I'm rolling down a hill and the little red light on the gauge will come on.


Truck is running like a dream though. Someone told me the truck should be stalling out around 10 and not having any power. Well even when it's way over 15 truck is still running beautiful.

Any ideas, maybe just a bad censor. Didn't do it when I got the truck, but it's now doing before and after new filters