Is it spluttering/cutting out then stalling?
Here is the first step: Get a can of CO contact cleaner, any repco has it, ask for it by name! When the car is dead cold(if the afm is hot it could f**k up), remove AFM, spray with CO contact cleaner, make sure it gets a good clean, alcohol based, dont touch the hot wire with any instruments, it will dry! Refit AFM, check all piping, and inlet piping, if symptoms persist which i doubt they will, refit standard BOV.
Check all wiring, especially earths. I honestly would take it too a mechanic.
The money you spend changing shit around could be spent getting it done right.
-Ryan