2005 Nissan Titan LE Gas Knock Sensor

I have a 2005 Nissan Titan LE Gas w/ 197,000 miles throwing a Bank 2 knock sensor code and a cat below threshold on bank 2. I had the exhaust manifolds replaced last year w/ Dormans. So I really don't think that the cats are stopped up. Could the knock sensor be causing the cat code? First time I took it to the shop they said cat 1 and cat 2 where below threshold (i knew cat 2 was throwing the code that was the reason for it to go to the shop but that was the first time cat 1 threw a code) and the knock sensor code but the found a loose pcv hose and tightened it up, cleared the codes, watched everything and it seemed fine. Well I picked it up and drove 17 miles. Bam light back on so I took it back to the shop now they are saying all 4 o2 sensors are bad and of course the knock sensor also. Both times they said run seafoam and it should be fine. I don't know about that. Opinions?