slight miss under load

[CalgaryGN]

Hi I am jsut wondering what could be causing this. I have replace the coil pack but not ignition mod. Also have new wires, new acdelco plugs gapped at .035, new high perf fuel pump and new 02 sensor. The car drives fine around but around 12-15 pounds of boost the car seems to miss and/or the boost gauge kinds of flutters. I let off when this happens and don't do this much. Slowly after the listed maintenance this problem has gotten significantly better. Very slight now. Just wondering what it could possibly be ?? I will be cleaning out the Ic soon as well as adding a hotwire to the pump. I am soon going to change the module too just to see if this is a prob. Any other suggestions ?? Thanks