P0420 Code help

When it rains it pours.. Seems like Ive hit a point were my truck needs alot more work all of a sudden.. anyway..

A few months ago I got a P0420 code.. There were several pinholes in the pipe before the cat where a shield had been and after at the cat/muffler flange.. I had them fixed and reset the light.. It stayed off for a few weeks. It came back on so I figured its from around town driving so I seafoamed it and made sure to drive it on the highway more.. Well, again it stayed off for over a month but just came on over the weekend.. Any ideas on where to start? before I just replace the cat as recommended by my local shop.. Ive seen where its been everything from a dirty maf or fuel filter to both cats and o2 sensors..

Thanks

 

The lights been off but I can not get it to achieve readiness.. Any suggestions?

 

still no pending codes but catalyst still incomplete.. Ive done toyotas procedure to get that monitor ready several times... hmmm

 

Did you ever get this fixed?

All I need to to is get my monitor ready also
I have done the drive cycle as toyota describes a milloin times and Mine still wont reset. it's been well over 6 months