bad cats?

[cody994x4]

ok so im still chasing the p1151 code. im starting to think its one of my cats clogged up or gng bad. ive noticed a rattle from the front drivers side getting louder and louder and occurring more often. so my questions are:

can a bad cat. cause a p1151...which is lean or rich in bank 1 sensor 2

and secondly are there catalytic converter insulators or heat shields on my truck?

i will most likely goto high flow cats....but what abt the pre-cats???