We have a 93 4 runner 4x4 6cyl we had the diagnostics test and it had a code of 52 which is the nox sensor which we had changed along with the wiring the check engine light would still come on and make the 4 runner slugish. We then had the fuel pump changed, fuel injectors changed, computer changed, egr cleaned and checked and still getting a code 52. We are at a loss and alot of money spent . We even had another nox sensor mounted in a different place because we were told that could be the probpem. But it was not. Any thought as to what could be giving us a code 52? Thank you