Hey folks, I’m trying to determine the cause of a random misfire in my Altima. I’ve checked my plugs and coils and that’s not it. Cleaned my vvt solenoids. Two things I do know, my valve covers are leaking and the intake manifold runner control valve is hissing like there is an air leak. Would that in itself be enough to cause such rough idling, random misfires and serious decreases in fuel economy? I’m not throwing any other codes other than p0300 so I don’t know where to focus. Any ideas are much appreciated!