Mine failed three times

Lucky u.  Mine failed the third time, Toyota 4Runner 2001, ,280k miles/ 2nd owner since 2003.  The catalyst is incomplete. I have done all I can, fixed an air leak before intake, took down the cat, examined/found its clean, so I put it back.  I have driven 500 miles in the past three weeks yet the truck is still not in ready mode.   Damn this is getting ridiculous.