Okay, My car has 16k miles, and past few weeks i've had a really bad idle. Just tonight I did a gauge test and took a look at the rpms. In Park or Neutral, my rpms will range from 630-820 rpms, it's a very rough idle. This can't be normal, the only things done I have done is a fc2pc pulley kit and a borla exhaust, but I don't think they did this right after i did those two mods. Bad plugs? bad wires? bad engine? any ideas? I think i removed the resonator off the stock intake, could that effect it too?