Are they the correct Champion RN10PYP4 spark plugs? Treat this and solve as a P0300 fault.
Fuel pressure check OK? Sample some fuel from the fuel pump into a clear plastic bottle and make sure there is no foam or excessive bubbles along with the liquid fuel.
Any sign of fuel or oil carbon fouling on the plugs that you removed?
Fuel pressure check OK? Sample some fuel from the fuel pump into a clear plastic bottle and make sure there is no foam or excessive bubbles along with the liquid fuel.
Any sign of fuel or oil carbon fouling on the plugs that you removed?