Are you sure you didn’t tear a crankcase ventilation hose or something, while you were checking out the car?
Or maybe you forgot to reconnect a vacuum hose?
Here’s some other possibilities for P0171 and P0174
Low fuel pressure
Exhaust leaks upstream of the oxygen sensors
Intake leaks
Brake booster hose
etc.
see i never got thouse codes till i replace the old maf…
@mwkarrick
Was the new MAF an exact replacement for the old MAF?
Is the replacement MAF a new part, or a rebuilt?
Perhaps the replacement is simply defective
It would explain the P0171 and P0174
The fact that the engine runs well with the new MAF . . . but runs poorly with the old MAF . . . confirms the old MAF was faulty
The fact that the P0171 and P0174 weren’t present with the old MAF makes me think the replacement MAF may be a dud
With all these rebuilt parts out there, it’s not that rare of a situation to run into a bad “new” part
the part i got was Remanufactured maf
i got it from autozone