Low RPM Vibrations

[Static6]

I have a 98 LX I4! Whenever I stop at a light or even after I park and let the car idle, the car will fall below 500 RPMs and will vibrate and shoot back up between 500 and 1000 RPMs. I installed new NGK spark plugs and the problem still occurs!

 

[RedRyder]

No CEL? Check your IACV and EGR and clean them. If it's neither of those the next thing I might check for is a vacuum leak.

 

[Static6]

Yeah the CEL is on and the Mantainence Required Light! I'm going to get it read today and see from there. I'm sure both of those need to be cleaned since this car sat up 3 years before I previously started back driving it.