What does it mean when car only jerks when traveling a long distance?

Not Knowing what type of car you have doesn't give me much to work with. But Ill try it could be a couple different things. The torque converter solenoid could be one they tend to do this after you reach highway speed and then drop to a lower speed, In most cars this is allot of work but does not require the transmission to come out. #2 It could also be a miss-fire that shows up after the car has reached operating temp (Heat = resistance for electrical components) and allot of heat builds up under the hood over time this would cause a small leek some place in the ignition system to show up after driving for a while. Any way hope this helped Good luck Don