swaped and still not happy

[PA3.4l]

Frustratedpa3.4l 3-18-2009

A little history... 98 boxster 2.5 swaped to 3.4l in 2007 ran it for a year and was not overly impressed. Thanks to board members found that I had the boxter program in the ecu. Had ecu reprogrammed and the car really takes off and revsto 7200rpm. yeeeeeehaaaaaaa. I am very happy with the power but since the remapping of the ecu the car will spuratically act as though it is misfiring at 2500-3200rpm under light acceleration. Problem is that it is very hard to duplicate.

Things I have noticed....

• No cel lights
  
• If in neutral and I gently rev the engine to 3800rpm I can hear the same sound as when driving --like a back pressure issue??? could exhaust be causing the loss of power???
  
• Drive hard the car runs fine
  
• Cold weather car does not act up at all ....Could it be a maf thing .. I know cold air is denser so is my car starving for air under low exceleration in warm weather >40.C
  

Since its hard to duplicate how do I go about fixxing the issue are the some test that can be done

The box has Dansk headers and 100cell cats and ghl exhast with 3.4l 996 motor.

Thanks in advance for any input