P0300, flashing check engine light

What is your question?

I have changed the spark plugs, in doing so also changed the valve cover gasket and all 6 spark plug seals. Also changed the intake manifold gaskets. Changed the purge valve solenoid Light still flashing and still rough idle and stand still.

How long has your 2012 Chevrolet Malibu had this problem?

Not sure, just bought it