P0134 OBD2 Error Code Reappears on 1999 Toyota Solara After Oxygen Sensor Replacement

Hello everyone, I'm having a persistent issue with my 1999 Toyota Solara. Approximately two months ago, the check engine light activated, and an OBD-II diagnostic scan revealed error code P0134. I initially replaced the first oxygen sensor, but the check engine light returned. At that point, I was advised that a second error related to the third oxygen sensor—located behind the catalytic converter—was present, so I replaced that sensor as well. After clearing the codes and driving the vehicle, the check engine light came back on after about 35 miles. A new OBD-II scan confirmed P0134 again, even though both oxygen sensors were recently replaced. The wiring harness appears to be in good condition with no visible damage. I've heard that the OBD system requires three consecutive successful tests before clearing the P0130 code—does this mean I need to drive longer for the light to turn off? Or is there another underlying issue causing the recurring P0134 error? Any insights or suggestions would be greatly appreciated. Thanks in advance!