2005 Nissan Altima 3.5 SE and the only two engine mods that I have done are the "Nismo CAI" and the "AT Grounding Kit". I started to notice my idle dropping below 700 to around 500ish makn it shake but then goes back up. It does this when I'm sitting at a light or something. This morning my engine light comes on, I scan it and get P1402. I cant get much info on it except that its "EGR" related. Now, does any1 know what steps I should take to figure this out. Or perhaps I should bring it to my dealer as I'm under warranty and this "might" be covered. Any help would be great, thanks!