Hesitations, and backfiring in the exhaust especially, is usually due to a lean condition or an ignition misfire.  If the backfire is loud, staccato, and violent, it's usually due to not enough fuel.  Bad ignition timing can also mimic these symptoms.  Please make sure the car is in good condition before trying to troubleshoot these types of problems.  We have a basic tune-up page here:
FC3S Pro - FAQ, Basic Tune-Up

Questions?  Comments?  Send mail to:  reted@fc3spro.com