idling at 550 then wanting to shut off

[MazdaSpeed4Her]

My Car started this the other day it will idle at 550 then drop down to almost shutting off. where the battery light comes on then goes back up does anyone know what the problem could be?

my mods are aem cold air, and 2.5 custom turbo-back exhaust

 

[evilmonkeyMSP]

is this after it has been driven, turned off and then when you restart it?

 

[MazdaSpeed4Her]

After i start driving it, its like when i'm coming to a stop