Thank you so much for the advice!

Would a faulty gas cap cause p170/173 codes? Or is that solely and separately caused by the MAF Sensor?

Does the gas cap fail often? Has anyone replaced their gas caps?

Also, I do have a vaccum tool, how do I go about diagnosing the system? Any hints?

Once again, thanks for all of your great help

Oh btw, is there any cheap alternative to the SDS? I know the dealer ones are costly, but is there a simplied version or cheaper version for DIYers?