2000 toyota 4 runner trouble code PO 171

Can anyone tell me what the code means and how to do the repair? My husband is a retired mechanic so we're hoping we can save by having him do it. Thank you for any help.

Clean the filament in the MAF sensor or replace the sensor if cleaning doesn't work.

Other less likely possibilities:
Vacuum/intake leak downstream of MAF meter
Inspect fuel lines for cracks, leaks, or pinches
Replace fuel filter
Check fuel pressure at the fuel rail
Check output of HO2 sensor
Check injector performance
Check ECT sensor
Check PCV valve and hose connections