Not sure what to check first
The car is in limp mode,you will have to have it scanned to know the real issue.
I was looking for an answer to my problem and ran across yours. I had the same problem with my 2009 chevy impala. I replaced the gas pedal and work just fin. The engine power reduced message went away and drove like normal
Looking for a Used Impala in your area?
CarGurus has 25,692 nationwide Impala listings starting at $900.
Search Chevrolet Impala Questions
Chevrolet Impala Experts
Related Models For Sale
Used Cars For Sale