I would definitely say it was a coil or a bad plug. You could take it to any auto parts store and get them to run a free diagnosis with one of their handydandy little computers. Are you getting a check engine light at all?To bring this interesting thread back to life.
I have 187k on my '99 LC and just the other day has been running rough and missing. I was told that it may be a bad coil, but a trip to the mechanic shall tell the tale. Any ideas, please feel free to shoot them my way.