Just a follow up on the blinking check engine

Just a follow up on the blinking check engine light.Thanks for the incite.The van has 150,000 miles.I've since changed the intake manifold gaskets with the new upgrades.Also changed plugs and wires.Torqued rockers to specs.Checked wiring harnesses on right side of engine(no chafing)fuel rail purged,resistance ok on coils.Ran system flush on engine,fuel ,old coolant systems.#3 cylinder seems to be the one shut down judging from plugs.Upon startup check engine light not blinking at idle but blinks upon acceleration and pinging coming from #3 cylinder.Could this be a rocker push rod problem or related to the bad converter 02 sensors.Sorry no compression check.Thanks again