2000 SL2 engine problems.

I have a 2000 SL2 with and automatic tranny and 106k miles on it. I know the timing belt needs to be replaced soon as the dealer had no record of it being done but I don't think thats related to my issue. On my way home tonight, keep in mind I drove it off the lot yesterday, the engine sounded rough. It was running with a stutter and every few seconds the tach would drop by 500rmp and shoot back up to where it was. When I got on the highway the tach shot up to 6000rmp before shifting. The Check Engine light was flashing when the engine stuttered but stayed solid on the highway. I've read that a lot of Saturn's from 98-2002 experience cylinder misfires. Any ideas what it could be?