Fuel Cut = O2 Sensor?

[Merrilin]

I've had a fuel cut problem (engine cuts power violently at high rpms/full throttle) for a while. My car recently clunked out - I turned it on and it sounded like a motorcycle - as if it was running on 2 or 3 cylinders. I towed it to a mechanic, who discovered that my exhaust was basically falling off (blown gaskets, loose bolts). I'm not knowledgeable enough to investigate these things myself. This was fixed and it was brought to my attention that the pre-cat O2 sensor is also faulty, and I was wondering if this could be the cause of my fuel cut problem - it seems to me like faulty feedback from the O2 sensor could definitely cause the ECU to wrongly cut fuel. I haven't fixed it yet because I'm going to replace my whole timing belt + related things as well and I want to buy the parts myself. I can only find one timing belt kit and there seems to be lots of different kinds of of O2 sensors. Does it really matter which I get?

Edit: I originally thought that my fuel cut problem was due to a faulty wastegate actuator (a mechanic told me mine was faulty). I even bought a new one, but when I went to have it replaced along with fixing my car, I was told that it didn't even need to be replaced (different mechanic).

 

[Preferio]

In all likelihood you were told that it needed the bank 1, sensor 1 oxygen sensor because there is a P0131 dtc stored in the fault memory. I've seen it on another MSP and my own. The dealership I had purchased mine from had replaced the O2 for that reason, but the code immediately returned. Once I purchased the car, I drove it 220 miles back home and it had fuel cut out, so I brought it into my shop that morning and smoke tested the system to find that the charge pipes were leaking. Applied a small amount of lubricant to all the charge pipe joints, and tightened all the clamps. Smoke tested again and no leaks, cleared the fault memory and it corrected the P0131 DTC and the fuel cut. Hope this helps.

 

[Merrilin]

I'm not sure how my mechanic deduced the problem, but what he told me implied that my O2 sensor got a lot of abuse because my exhaust was so messed up. This leads me to believe that it's a physical problem with the O2 sensor itself, although I'm unfamiliar with charge pipes. Is it worth asking my mechanic to check for any leaks when he does the belts and O2 sensor?