2001 Chevy Astro cylinder 6 misfire code

What was the code? A P0300 is a random missfire, it may be a problem that is common to all cylinders. If the codes is cylinder specific, that's where you start looking. A misfire can be caused by fuel--spark--compression, just about anything.

Can you check the circuits at the maf sensor? Pink wire is voltage with the key on, black wire is ground, yellow wire is signal, the signal should change with air flow. You could try the tap test, see if the signal changes.