Could O2 sensor cause a very, very severe rough idle?

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Hey, If anyone is familiar with Ford Escort ZX2s and a very, very, VERY rough idle, I'd really apprecaite your advice. The car's always had a rough idle - either when at a stoplight and the car's in drive but stopped or sitting still. When I shift into neutral the idle gets smoother but there's still a slight vibration throughout the whole car. It's now gotten so bad that even shifting to neutral doesn't help. Literally the steering column vibrates about an inch up and down and the entire seat shakes. I thought it was the motor mounts so I ahd those replaced about 6 months ago but it didn't do much. The only thing that I can think of is before my alternator was replaced, the check engine light was on and the code was for a bad O2 sensor. Could a bad O2 sensor make the car idle this roughly? Since they unhooked the battery, the light is off now and I can't get the code to see which sensor it is. Would it be helpful to replace the sensors to correct an extremely rough idle? Oh, I notice that when the AC is off, the vibration is't as bad either. Thanks for your help.