My O2 sensor reading jumps around like mad while I'm driving. Is there a fix?

No - this is normal.  You are viewing the ECUs attempts to supply exactly the right amount of fuel to the engine to achieve stoichiometric operation (equal masses of fuel and air).  The cycling also means your O2 sensor is healthy.

For more information on how the oxygen sensor is supposed to behave, read the The Essential Primer on the DSM ECU.