You're going to have be a bit more specific. When, exactly, does it hesitate? Warm, cold or both? Off-idle or at higher loads? How severe is the hesitation (small hiccup or full-blown misfire?)
What mods are on the car? When did it start showing symptoms and did the onset correspond to any service/work you did or had done to the car? When I say "any" I mean any, from cleaning the car or engine bay to have long-tube headers installed...
Do you see a MIL (malfunction indicator lamp)/service engine soon light?