MAF and O2 sensors

My check engine light turned on and got it
scanned. It came with a P0171 and P0174 code
and suggested that the most likely solution would
be to replace de MAF sensor. DID IT but the check
engine light still is on after 60 miles of running the
car. Before changing the MAF sensot I also had
gotten another estimate that included replacing
the O2 sensors but since the scanning came up
with only having to replace the MAF sensor I
decided to do just that. My question is if I should
change the O2 sensors inmediately or if there
could be something else causing my check engine
to stay on. The total to change MAF and both O2
sensors was about $920. The MAF has been
changed so I'm guessing the new total would be a
little less, but I'm trying to save some money and
want to find out if the problem could have another
cause besides the O2 sensors.