Rpms+vibrating+light

Well About 2 days ago, I noticed That when i stop at a Red light, My Rpms are at like 1000, then it goes down.. and my lights flicker a lil bit, and go up , and keeps doing this. And Then my Car irregularly vibrates during this time when the Rpms are doing this. And on top of it, My Service Engine Soon light came on, So something has to be wrong right? I was just wondering what it could be, I plan on taking it in, But i would just like to know what im in for.

Thanks.

Welcome to AF.

Please post the year and model Grand Prix to include mileage.

Since the SES/CEL is on get it scanned to see what diagnostic trouble code(s) are present.

Its a 2000 Grand Prix GT, 75k Miles on it, And i could get it scanned but i might as well just take it in and have them fix it and stuff, i was just wondering would could be wrong with it?

Hard to say. When was the last basic tune up? Spark plugs, ignition wires, fuel filter, air filter? Possible dirty/carboned up throttle body, idle air controller (IAC), MAF sensor, vacuum leak, fuel pressure. With the SES light on it is best to get it scanned otherwise we would just be speculating.