96 Pathfinder 3.3L throwing P0420 on a new catalytic converter.

Question

L & R cat converters replaced with rebuilt engine drop in
O2 sensors  ( 4 )  new.
Distributor new.
EGR valve new.
Backpressure transducer new.
Plugs and wires new.
Leaking vacuum hoses new.
These items were all replaced clearing other DTC codes.

Answer 1

New would not necessarily mean it works , the best way to resolve this is to check the data stream a good working rear 02 sensor which is the downstream 02 sensor should stay .650 volts at idle and snap throttle no more than 20 seconds.

 here a sample that you may encounter this is a rear or the down stream 02 sensor that set a false P0420 code