I noticed after about 15 minutes of highway driving, keeping it around 3-4k rpm and coming to a stop my rpms would drop a little but would kick back up and be fine. Just yesterday, however, I was driving and got two blocks down came to a stop and my idle dropped to around 600 and it sounded like it was only running on 4 cylinders and the service light came on. Immediately hit a U-turn and started driving it back home, sounded like a flat-4 for a minute, then kicks back to normal and the service light turns off? I'm really confused and don't wanna drive it anywhere until I can get it checked, but was wondering what it could be or if anyone else has had a similar experience.