1997 Isuzu Rodeo 4x4 3.2L Automatic

My Rodeo is idling a little rough with rich, black exhaust. I can clear all codes, and, within one day, these three come back, P0131, P0171, P1133.

I have the code definitions but don't know what to gather from the info. <img src="/forums/images/graemlins/confused.gif" alt="" />

I have installed a new O2 sensor on the front, drivers-side.