The knock and crank codes could be due to the choppy idle from the crappy MAF. My MAF went bad last year and I was able to source a spare to try from a buddy with a 300zx, just to be certain after already seeing a code AND taking readings from a volt meter.
If you're neurotic like me and that MAF code isn't good enough to be certain, take readings with a volt meter to further pin point a MAF issue 👍
If you're neurotic like me and that MAF code isn't good enough to be certain, take readings with a volt meter to further pin point a MAF issue 👍