Car Wants To Die

hi there, i installed an hks intake and a greddy type s bov on my 03 lancer evolution this weekend. i capped off the hose port on the intake so i could blow off to atmosphere. (sounds too cool). when rpms are tached up and when the throttle is closed the rpms drop fast and then the car boggs down and sometimes stalls. i'm sure that this is because of the bov setup. i'm wondering if someone can explain why it does this and if there is a way i can fix it with still being able to b-o to atmosphere. there are currently no other mods to the vehicle. soon i will be putting on hks exhaust, apex-i safc 2, greddy turbo timer and a manual boost controller. i like to think i have more than basic car knowledge but am new to owning a turbo equipped vehicle. oh there are no diagnostic dtc's stored in ecu.
thanks alot. :stick: