The Electronic Throttle Control light is on?

The vehicle listed above is the High-Altitude Edition.

Electronic Throttle Control Light is on. I have replaced the Throttle Body and the gas pedal, and it is still on.

I do not have a problem with power, and I can drive 100 mph on the highway if I want to with no issues.

One big noticeable issue is a shudder when shifting.

The car has an automatic transmission.

The Code that appears on the checker is P2123 and it will not clear from the device, the throttle body will not reset using the startup/hold gas pedal technique, and the code will not clear when trying to erase it with the checker.

Also, even if I take the battery cable off the Electronic Throttle Control Light comes back on immediately when I put the battery cable back on. It's not something that the engine needs to deem bad after driving x number of miles. It knows immediately.

Lastly, as a by-product my cruise control, remote start, and auto-stick (being able to manually shift an automatic transmission) all do not work anymore.

I'm going to guess this is an ECM issue, but I'd like some feedback before I purchase a new one as it isn't cheap.