Plugs and wires.
I had the same problem (symptoms + P030x misfire codes/flashing CEL) and resisted doing plugs/wires since I had recently put new ones in (Ford racing wires + Autolite APP764). Apparently I had received bad wires or plugs because when I replaced them all with Autolite wires + APP764's the problem went away.
FYI the flashing CEL means misfire is occurring at that moment, so that's more of a reason to do the plugs/wires now.