00 jdm b18cr w/mugen chipped ecu, stock internals---- idles fine when cold-1200....when warm at stop it will fluctuate from 800-200 rpms or so and almost sound like its gonna bog out but wont.....doesnt always happen but most of the time will..... any ideas what it is?

 

god a system in it? im drawing 3000 watts, and when it hits, it draws a LOT from the alternator. thus lowering my rpms from the lack of electricity...fun to watch

 

no subs or anythng....the only electricity im drawing is from my fan switch and a little from an amp pushin two 6x9s