'02 Frontier desert runner 3.3L v-6--reccurring 2 codes--camshaft positions sensor, and knock sensor. Here's history: Replaced distributor,cap, and button(cps is integral part of the distributor), after cps tested bad with ohmmeter--ran ok for awhile--same 2 codes surfaced. Replaced plugs and wires--same deal. Cleaned ground point for both sensors--same deal. I run Techron fuel cleaner regularly, and fuel filter has been replaced. Air system is clean as is throttle body. Any ideas?? Hate to replace knock sensor as its UNDER the intake manifold--computer problems???? anything would be appreciated!!--eroc