Had the same issue. Owner before me had the same thig replaced the O2 sensors. I did it about a year later and it just seemed to be a temporary fix of 3-4 months. After consulting with a local 4Runner mechanic and the internet I finally opted to replace the cat convertor. Since doing that over 2...
Went to get state inspection done. Totally forgot I had disconnected the battery a week ago to test something out.
Don't forget to drive 50+ miles for a reset before getting your inspection done -_-
Something about the 3rd gen just does it for me. Maybe it's a nostalgia thing. There's something even about the way a 90s truck smells that makes me want one. Working on tracking a 4WD near Texas currently.