1998 Dodge Dakota Sport, 141k, 4 cyl

Oil
Trans fluid
plugs
wires
cap/rotor
tie rods
u joints
brakes
and more !

You should go for the "if it aint broke dont fix it" angle.
But you should make sure all tires are safe, meaning no ddry rotting, uneven wear or otherwise damage. Check fluid levels and replace fluids if necessary. Most important thing would be the emissions though because it greatly affects your mileage. Have exhaust system inspected, along with pcv valve o2 sensors and your filters. And to just be on the safe side, go ahead and get a tune up. Your car will love you for it.