Have a 1997 Mazda B4000, 4.0l, automatic, 2 wheel drive that is throwing codes P0133 and P0153. Both banks have slow response. When I do a live read of system, all 3 O2 sensors are showing 0.000 after running for 45 minutes and longer. Read somewhere else that it may be caused by some other place. Not sure what else to do or where to start. Any advice or direction?