Check engine light came on. Is running a little rough....could it be bad gas? on 1998 Oldsmobile Aurora

Codes P0171, 0174, 0300 came up. How do I find out what they mean? Gas cap has been checked and is good.

Asked by for the 1998 Oldsmobile Aurora
1 answer
ck for vac leak and then misfires.vac leak may be causing misfires