#1: Have someone that understands how the air and fuel system operates on your car look at it
#2: When removing cats, you need to either run simiulators, or better yet, reprogram the PCM. This can be done by a custom programmer (such as using LS1_Edit or that other software that is out now...can't recall the name), or using a hand-held job, like a POS Hyperjunk, Jet-crap, or the Diablosport programmer.
#3: If it's a front O2 problem, go buy a new O2 sensor. But the O2 sensor will have nothing to do with how the car runs in power enrichment mode (typically 75% or more throttle application, but there are a lot of variables to this.....to make it easy, if the car runs like crap at wide open throttle, it IS NOT THE O2 SENSOR).