P1744 Ford - Torque Converter Clutch System Stuck in Off Position
so if the torque converter isn't locking, i would say yes, that is contributing.
when cruising at 60, I am right in the middle of my exhaust's drone zone... the drone zone is from 1800 -2600 RPM.
so I guess depending on what your gearing is, that may be reasonable.
do you feel it shift into all five gears?
... It's a v6 and only gets about 18-19 mpg. That's being really easy on the throttle.
rural mostly.
I think that if you want to do better than 19, you'd have to do mostly flat interstate driving.