Not sure if this is applicable for the 1998 model, but some of these
problems were blamed on cracking dashes which push on the wiring. I
have a 2000 model and was affected by it. Now reading you post, I
recall having had similar behavior intermittently with my headlights
to the extend that it went completely dark. My dash got replaced by
the dealer for free by now over a year ago and I have not had a
problem with the headlights since. Again, not sure if that has
anything to do with, just a thought.