Well, the MIL was acting up so I brought it in to the dealer to check today. He says it's a "coil" of some kind that's defective (some sort of electronic part I think), and that it's causing some misfires. So, it's a $500 part, and 1.5 Hrs of labour.
I thought it might have been the Mass Airflow sensor that was at fault (just got a letter in the mail about a warranty extension on that), or perhaps the O2 sensor (had the problem last year, didn't fix it because it went away when the weather got warmer). At least those two problems would have been under warranty...
So, after having the car only 3 years, I'm now out ~$700 (parts, labour, taxes).
@($#*!!!