Reduced Power

[cobra715]

Ok, what I've got is a rebuilt salvage Colorado. It's an 04' 4x4 crew with 37000 miles. It was hit in the front and the frame replaced. Now, it set for almost a year, thanks to my mechanic, and now after I have it all back together I'm getting a reduced power message on the gauge cluster. The truck sat without the battery in for almost that entire time and I don't know if something happened to the ecu. I have no throttle response from the engine and when I'm cruising on the interstate I don't get the acceleration that I should. It will usually sit around 2000 rpms and when I floor it doesn't down shift or rev. Does anyone know if there is a way to reset the reduced power message without having to go to the dealer. I have a code reader and it is saying that the engine is running rich. Any thoughts or answers are much appreciated. If you need more info let me know.

Thanks,
JB