02 Sensor Issue

Hi all,

I’ve been having a bit of an issue trying to fix what seemed like a simple problem. Had a check engine light and was getting code P0420 “Catalyst System Low Efficiency”. Figured it was for a bad 02 sensor but went a while before attempting to change it. When I finally did, my check engine light went off but the truck seemed to have a rough idle and when driving seemed like it had a small sputter. Just yesterday while driving, the light came back on but when the code I got was P0120 “Throttle/Pedal Position Sensor ‘A’ Circuit”. The truck will feel like it wants to run and idle steady for about 30 seconds then goes back to a rough idle between 500 and around 1000 rpm. At this point I’m not sure if I just got the wrong sensor and it’s causing other Issues or if I should actually replace the TPS. Any tips will help Thanks!!