Miata Turbo Forum - Boost cars, acquire cats. - Turbo Miata stutters at 4500-5k rpm, then pushes through and hits full boost

Hello, I have a turbo 93 LE Miata with a built 94 1.8L motor. I've got a FM big fuel kit, and ID1000 injectors and Toyota COPs. I'm using a MSPNP pro. When I hit 4500 rpm I get a stutter, almost like my car is hitting launch control. If I stay steady on the throttle it will usually just keep hitting the stutter, however if i give it more throttle, it will eventually break through the stutter and immediately hit 14# of boost. If I am very light on the throttle, I can rev the motor without hitting the stutter. I have had a buddy look at my fuel map and my timing table, and he said they both looked fine to him. I even had him straighten out my map, however when I put the car on autotune, it develops a spike on the 3d fuel map. No matter what I do, the autotune keeps making the spike at 4500rpm. My AFR reads rich around 10 once it starts building boost at about 3500 RPM. It then reads really lean, about 16, once the stutter starts. Then once it pushes through, the AFR returns to being rich.

Any ideas what I might be causing what I am experiencing? I've done lots of searching for threads where people had similar issues, but keep coming to the same ones. Ive checked my grounds, replaced my COPs, replaced my spark plugs, checked my timing, I've tried gapping my plugs as low as .020. Nothing I do seems to make a difference.