Diwarn mabry

mileage is 125,897.I haven't changed the TB.Is there any way of knowing which 02 sensor is bad?

I have a 01 gs 300.Recently my cel and vsc off light started coming on.Early in the morning it runs fine.But one evening while I was driving home from work the car started jaking like the fuel filter was clogged.Then I felt two clicks in the gas pedal,then I had push the gas pedal to the floor to continue going.I removed and cleaned the throttle body but now I have a fast idle at times plus the mashing the pedal all the way down to move issue.The code was Po420.now it's Po1120. I forgot to mention while the engine is running u can hear a lil funny noise at times like a bad water pump pulley.The noise started around the time the cel started coming on.Could someone help me out?