Deleted the cat, still had the stutter.
Replaced the wires with some Taylors and all of my problems are solved!

My rattling noise is just about gone, I guess my engine just had to adjust to the new 1.9's. I'm getting KR spike though, but only as I step on the throttle right as it begins to downshift I get a 3.5-5° spike then it goes away. For the life of me I can't figure out what might be causing that!