2003 Chevy Tahoe Reduced Engine Power

From time to time, my Tahoe gives me the “Reduced Engine Power” error, and I lose acceleration capabilities and have to pull over. After a min or 2, I can go again, but the check engine light stays on. With no rhyme or reason, the light will be on or off on the next start up. The problem may or may not happen during a short ride or may happen quite often. I have replaced the Accelerator Pedal sensor, so that is not the problem, I’m assuming. I’ve been told that it is the Throttle Body that needs to be replaced, but no mechanic can confirm. They just want to replace it and the pedal for $700.
I would really like to keep this truck for a couple more years. Other than this problem, the Tahoe has been pretty good to me.
Here are the codes that have been read: P1125, 1516, 2120, 2125

Any help would be appreciated. Thanks in advance for you consideration.

Best,

Sean

This is to long to paste on here. Many years and many models have your problem. http://www.ssrfanatic.com/forum/f5/tsb-reduced-engine-power-15539/

I have no idea what is wrong, but I think that message “reduced engine power” may mean the ECM has put the vehicle in what they call “limp” mode. The ECM’s is so confused by the sensor readings it is getting it can’t figure out what to do, so it provides that mode so hopefully you can at least get home.

So, replace the throttle body. If mechanics say it might fix issue than at least it will eliminate 1 potential cause.