Since I don't know what your vibration feels like, it COULD be a worn U joint (rear wheel drive only) or it could be a tire balance or bent wheel problem.
Vibration , damage from sun exposure ,
U joint or tire would be the most common.
Worn/loose u-joints are very common.
Broken transmission mount? Bad "U" joint? Bad center bearing? Driveshaft out of balance?
Bad tire, bent rim, warped brake rotor, bad cv shaft........
Fuel pump is located in the gas tank.
Most likely a failed TPS.
The EPA range estimate for the 2014 Dodge Durango is N in the city, A on the highway.
you might have a router or caliber gone
The highway gas milage for a Dodge Dakota varies by vehicle. Average milage is around 16 mpg.
Balancing of tire/rim.
The EPA range estimate for the 2014 Dodge Avenger is 354.9 mi. in the city, 490.1 mi. on the highway.