Check out the website regarding P0171 & P0172.
It gives general info regarding cause/symptom/solution.
Since MAF sensor(s) have been replaced, I doubt that’s the problem but
I’d give it a good clean and check around the MAF sensor(s) for any build-ups
and check for any leaks with vacuum hoses.
For simple fixes, it isn’t much of a problem replacing
unfortunately, there are limits on how much a non-mech could do…
Best solution
1. research/google the code and see what can be done