The truck has 108k miles on it. It seemed to run worse for a little longer one time about a week ago when I was very low on fuel (bottom of orange). If a fuel pump would also affect the sender that's another possibility. I filled it up and it stopped at only 20 gal so I should have had at least another 3-4 gal of space according to the gauge. My ultragauge also never reads the fuel correctly and says something like "cant find fuel sensor" when trying to access things in the menu. Not sure if this is the same for everyone or if it's an indicator of a failure.

 

IMHO the Ultra Gauge might not find the fuel sensor since it does not route via the ECU, it goes directly to the instrument pod. Certainly it does go thru ECU on some vehicles.

 

Dont use the UG for fuel level.
I change my answer, bad fuel pump.