I have a 2007 Chevy cobalt that shows a reduced engine power error. The problem is sporadic sometimes it will run like a sewing machine and other days it will show the error and shake like it is about to cut off. I took it to the dealership and they told me to replace the engine. I don't believe that is the problem because it runs fine some days. If the engine were bad would I believe it would run bad all the time. Anyone having the same problem or maybe know where I can start to fix the problem.
A common culprit for that error is the throttle by wire system. If the car senses that something is the matter with either the throttle body or the gas pedal it will reduce power. The best way to verify this is to have the codes pulled. You should see a code for the throttle body or the gas pedal.