vortechysi

I have a 1993 mustang gt with a 306 and a vortech ysi charger, had the car tuned and it still is giving me problems. Have all the internals done and fuel pump and all, stc chip and 42# injectors why is the car still bucking when I drive it and it gets up to 2800rpm's. The dyno shop has had the car for 3 months now and they still haven't figured it out yet, they say the motor is fine but it's just seems to not be getting enough fuel. Any sugestions.