Which catchcan are you running? The oil ingestion is one of the #1 cuases of this. Look at the bottom of the intake manifold snout (just behind the throttle body mount) and there is a cast in sump to cathc some of the oil....when it gets partially full some big sluprps of oil get pulled in all at once causing the misfires.
Pull your TB off and stick your finger into it and see how much oil is there. May be that simple.
