I just gutted the cat today. Figured there is no harm since I need to replace it anyway. Throttle response seems way better, but its hard to tell. Still idles weird and the lights still flicker.

My O2 sensor is ok. It makes no difference if its plugged or unplugged. I also replaced it recently. My OVP is also fine. Swapped it out with a known good one. No difference. Didn't get around to testing the alternator yet.