You could try cleaning out the inkate runners. Mine were absolutely disgusting, so I cleaned them out with some rags and a bottle of fuel injector cleaner, and any left over I dumped into the tank.
And while your in that area you could do the vacuum/coolant line cleanup. Because your vacuum lines are probably as bad mine were...
The cleaning of the intake runner may not do anything, but if your car has vacuum leaks, fixing that will help you out.
The o2 sensor is a good idea aswell.