The cheapest thing but an important one is to make sure your putting a good brand of gas in it. Also, add a bottle of fuel injector cleaner such as, Gum Out or STP. Clogged fuel injectors will make the engine jerk or hesitate. Is your car stalling out at times or rough idling? These are also signs of clogged or dirty injectors. I recommend adding fuel injector cleaner about every 3 months in older cars.
Bad plugs or a clogged fuel filter can also have this symptom you described. A loose plug wire can also be the culprit