KA-T part throttle sputter/jerking VIDEO

[coupe92]

hey guys...At part throttle, higher rpms (5000+) my KA-T will start jerking back and forth and the rpms jump up and down until I either let off or go WOT. The car is fine at WOT and lower rpm part throttle, I just can't figure out why I can't be part throttle at high RPMs. It's running an enthlapy ecu, 740s, n62 maf (12" from turbo) stock fpr (problem?) wally 255 and an ISIS t25/t28.

Anyone have a similar issue? Here's a video to help you understand.
Ka24det sputter problem.mp4 - YouTube (http://www.youtube.com/watch?v=w7MoqDlJTUo&feature=youtu.be)

Any help is much appreciated.

[AdamR]

What is your AFR like during that?

[coupe92]

Just checked, the AFR goes really rich, showing 10.0 on the wideband, where WOT is usually around 11.0. I know a boost leak can make you run rich but why at only part throttle does it have a problem? WOT is fine.

Also, my car runs the same with the o2 sensor plugged in or not. It has been this way ever since It was N/A, but I never threw a CEL so I didn't know if it made a difference. Could this be the problem?