is there a check engine light on?
how many miles are on the car?
will the engine hesitate if you give it gas in park or neutral?
does it hesitiate all the time ? or worse warm or cold engine?
any prior work or anything leading up to this probelm?
1. when you checked the fuel pressure what was the reading ? and did you test the pressure under load when it was hesitating?
2. have you physically inspected the spark plugs wires and igniton coil? checked for burn marks or cracks in the coil?
ok. the other things to check would be the ignition timing, the coolant temperature switch for the engine control computer, and then the map sensor.
you didnt say if there was any work prior to this happening? when was the last timing belt replacement?you may want to check the cam timing also.