still problems?

okay, replaced plugs ,filter ,pcv and camshaft sensor. my car stills stalls whenever it feels like it. although its more frequent now (once a day). the only code i get is 0172 (system too rich bank 1). do i just replace o2 sensors, because im not sure if that would cause stalling. and if other sensors were bad wouldnt i get codes for them? and if fuel pump/filter were bad wouldnt i get codes for that?