2003 Chevrolet Trailblazer reset service engine soon light

Did you read the codes again? Either the same code is setting or there's a different problem. If the code is for the same cylinder, try swapping the injectors between cylinder 2 and another one, then see if the misfire code moves to that cylinder. Also, there's always a long list of conditions that must be met for a code to set. One of those conditions is that certain other codes can't already be set. When there's a cylinder misfire code already there, some other self-tests won't run so those related codes won't be set. Once the cause of the misfire is solved, the self-tests will resume, then the computer may detect the next problem.