Assume you have read the first link below in my signature?
Are you sure the CCV lower oil return hose is good? If you have a cold weather hose, with the insulation, it will many times hide the bad hose. If the hose is covered with oil, it is bad.
You may have other bad CCV hoses as well.
MAF cleaner only works for MAF's that have oil on them. You could have a bad MAF or a non-OEM MAF that is under reporting the air flow. Usually a bad MAF will trigger the CEL at a cruise and not idle.
Even though you changed the valve cover gasket, you could have a cracked valve cover. Lots of small vacuum hoses under the rear of the intake that can get disconnected or go bad.
You have to figure out if you have a crankcase air leak, a vacuum leak in the intake path or a bad MAF under reporting the airflow.
Do you have the ability to read the MAF Grams/sec airflow and fuel trims? This may help, otherwise a smoke test may be needed.
Smoke test both the intake path and the crankcase.
Last edited by jfoj; 11-13-2012 at 06:45 AM.