How can I check the ECM is working properly and is there another throttle pedal position sensor besides the one on the pedal that I can change

What is your question?

Replaced throttle pedal position sensor throttle position sensor engine coolant sensor and thermostat cannot clear check engine light or reduced power engine light code is p0123 for the throttle pedal position sensor but I replaced that. Is there a way I need a reset the ECM or does it need to be replaced?

What makes this problem better or worse?

It's constant, it starts up and runs but when I try to drive it but there's very little power. The temperature gauge isn't working and there's a third light on the dash dad I believe is a gauge light only that have anything to do with the reduced engine power?

How long has your 2005 Buick Rainier had this problem?

Months