Hesitations can be caused by numerous problems. The thing is you have to look at the engine mileage, service history, including quality of parts used for servicing. You have to get the thing diagnosed first rather than just start replacing parts and hope that sooner or later you will fix it. Some people choose to fix problems themselves , others just pay the experts with the correct gear for your cars problems.
Fuel systems, electrical systems etc have numerous parts all of which can cause problems. Which part.......????
Al.