Ponys running rough

[Slimer93]

I've got a A/F meter that wasnt reading anything due to shot o2 sensors. So after I replaced the o2's the A/F meter started working (and I got about 2 mpg back, up to 15 mpg). I was wondering if its normal for an a/f meter to start going erratic when the engine warms up. It goes from stoich to lean and back over and over. If I give it some throttle it will act normal until I back off. Could this be a MAF sensor problem? Ive got the weenie stock unit. And I say my cars running rough because since ive put the o2 sensors in it seems like I dont have as much low end, it just kinda drags along until my boost makes up. Any suggestions??????????