Oxygen sensor code

My 91 Firebird 5.0L TBI has started hesitating badly when cold. In neutral idle, it alternately revs then slows in about a 5-second interval until it stalls completely. It will rev up okay if I open it up.
In drive, with light accel. pressure, it seems to miss about every other fire. With heavy pressure, it barely fires at all. I can get the car to accellerate if I pump the pedal rapidly but lightly. As the motor heats up, it suddenly starts running nearly normally. I've replaced the fuel filter and the injectors appear to put out a healthy spray. Occasionally the "service engine soon" light comes on and I read an O2 sensor error code (44). Could a bad O2 sensor cause this engine operation?
KW
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It is more likely unburned fuel is causing the O2 sensor code. Have you looked at plugs, wires, etc...

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