Well, A lot of this seems like map sensor/ecu confusion about boost. You may very well need to acquire some sort of fuel mapper device. Can you describe more acutely what the problem during driving is?
Does it stutter RIGHT when you stomp on the throttle OR when boost starts to set in? If it stutters when right when boost sets in, you're in need of a vc1/fuel mapper/ FCD. If it stutters immediately off-the-line, then it may be your spark, vacuum lines or your fuel delivery.
Hope this helps.
Jason 98' Eagle Talon ESi-T Mitsu Super 16g Turbo(HRC)