did you check the Cat?? I read you checked the VCT Solenoid, but the people here are suggesting you check your Cat.
Maybe, you should check that. Take it a muffler shop if you want them to check it.
Or if you have an OBDII Reader, unplug your cat and run your car for a couple of minutes. IT WILL BE LOUD ... but if the headers don't turn red, and all you get is the 2nd O2 sensor issue, then it's your cat.
And the code for the O2 sensor would be because you would be doing this test with out the cat in.