Originally Posted by Fabrik8

My advice (via PM) was to check the wiring, then check the ECU. Having that many sensors be faulty at once usually means that they aren't getting sensor power or ground from the ECU, or the ECU has died. There is always a reason that things appear to go bad all at once like that, and it generally isn't because four sensors actually failed at the same time.

And I ALWAYS suspect crappy engine swap wiring. Always, always, always.