Dodge ram 50 2.6 barley can hold 70 on interstate

[SubGothius]

70 MPH should be no problem for a stock 2.6 in good running order, so check the usual basic tune-up stuff -- esp. make sure your static ignition advance, centrifugal and vacuum advance are all within spec. and functioning correctly.

[FMS88]

70 MPH should be no problem for a stock 2.6 in good running order, so check the usual basic tune-up stuff.

I agree completely. Have you tested the engine’s compression? Acceleration and top speed will suffer if one or more cylinders has low compression.