Diagnosing a bad maf sensor

Noticed a sulfur smell from the wife's 2013 Equinox 2.4L and saw some dark smoke from the exhaust when she accelerated getting on the highway so i cleaned the maf sensor (3 weeks ago) and that fixed it but yesterday she said the sulfur smell came back. I checked the air filter, filter housing and all the connections and don't see anything loose or cracked so idk how the maf sensor would get so dirty so quick but cleaning it seemed to fix it for a while?

I know it could be the injectors, plugs, catalytic converter or a few other things. I'm wondering if it's worth replacing the sensor ($60) first before digging deeper into it or if I can rule out the maf sensor being bad or not. Thoughts?