I have a 1996 s10 with the 4.3 motor and the exact same codes it also threw every o2 sensor code in the book along with the maf sensor. The problem was solved by fixing an exhaust leak an guaranteed that will fix yours also. Mine was leaking just in front of the cat and causing that o2 sensor to fault then the others trying to correct the problem. I was pulling my hair out for a good couple of weeks trying to fix this problem. If not the computer is the last resort but try finding an ehaust leak first. Good luck.