"ServiceNews Article - If normal troubleshooting suggests replacing the fuel injectors, check the long-term fuel trim using the i-HDS to ensure that it's fixed right the first time.
-If it is less than 1.0% (lean), then it's most likely caused by the injectors.
-If it is more than 1.0% (rich), then it's most likely caused by carbon buildup on the valves. Use a commercially available valve cleaner to resolve the carbon issue."