Reduce engine light

No the reduce engine power comes on an shuts me down only when I'm at a red light or idleing,I have changed out throttle body and pedal ,will bad motor mounts cause that problem I replaced those too

I believe the temperature was a little high what about O2 sensor in my bank one is running lean I need to replace O2 sensor can that be the problem

Engine has never got to the over heat mark but does go up and down at time ,qauge moves a little not alot only time the engine light comes on is when the reduced engine power in the traction control come on that's it I have changed the pedal I have change a throttle body I have changed Emi sensor motor mounts and the code po171 is popping up for my O2 sensor Upstream so I'm about to change that out but other than that I don't know what to do

What about me needing a tune-up what about the spark plugs and wires but what about thermostat