The senders are operating properly. They are providing the correct resistance value.
The last sender that I pulled is sitting around here somewhere. after I pulled it I hooked it up to the gauges on a test bench and they controlled the gauge correctly.
The problem is in the vehicle as a whole. I eventually will find the problem, my lips to Gods ears. There is some kind of FM going on here.
Maybe add some type of pull up resistor ( or some other invention not yet discovered) to strengthen the circuit from the tank to the gauge