Possible bad plug. wire, coil, injector.

Maybe.  This Series II engine is susceptible to the plastic plenum
decomposition problem.
When this cockiedoodie part starts going bad, it may well set that code as
the leakage
of coolant into the engine begins.

If this is the problem, the engine may soon lock up due to coolant in the
cylinders.

Now, there can be lots of other things involved too, but if you havent had
the old plenum
replaced, this could be a signal that your time is nigh.