96 ranger codes need help

i have a 96 ranger xlt with a 2.3 5sp 2wheel.it has in order codes p1443 and po 420 i found info on po1443 i am checking vacum lines and will probly get the purge flow sensor if i find no leaks.were my trouble is i cant find anything on code po420 bank1 cat efficiency below limit so if any ford techs or someone that knows them could help me out would be greatly appreciated thank you.

You have 2 oxygen sensors. One upstream from the cat and one downstream. The upstream (O2) should have a reading that changes and the downstream (HO2) should be fairly steady. When P0420 triggers the CEL, the readings of the 2 sensors are similar. One reason for this is because the converter isn't working as efficiently as it should, but there are others.

A code 420 means one or more of the following has happened.

1. Leaded fuel was used instead of unleaded.
2. An oxygen sensor is not reading properly.
3. The engine coolant temperature sensor is not working properly.
4. Spark timing is too retarded.
5. There are leaks in the system.
6. The two oxygen sensors are too similar in readings.

To troubleshoot.

1. Check for exhaust leaks at the pipes, manifold and catalytic converter.
2. Inspect the downstream (HO2) and replace if necessary.
3. Replace the catalytic converter.