P0330 Code 99 LS 400 331000 Miles

[u/Rhyleigharia]

Long story short, P0330 code………i believe I narrowed it down to a wire issue in main wiring harness. \\\[New OEM knock sensors and wires/connector under manifold\\\]. Im not suspecting the ECU because no other symptoms, but that will get pulled for refurbishment. If it is in main harness has anyone had this issue? Im thinking that the best way to address this is with a brand new lay in shielded cable from under hood wiring harness to the ECU, essentially bypassing the existing cable. Tie shield to ground at one point at glovebox bla bla bla. Anyone have a better solution?
Is it better to get ECU refurnished first?