Hi Muz no problems with Advance Autos I got mine of them about 12 months ago absolutely over ther moon with it .They were very good to deal with and honest so what more can we ask for.
I don't have any stalling problems with mine.
I have a blitz cooler ,turbo smart boost cotroler,3" stainless system few other small bits and pieces.
Have you got a blow off valve ?sometimes if they are not adjusted correctly you can suffer idling problems.
My personal mechanic (SON) put a new set of iridium plugs in it the other day so might pay you to look at them to.
Probably better speaking to CYA34 he nows them inside out so he might be able to help you.
Ray tol;d me from Advance yours had a lot of nice goodies on it,it was still in the showroom covered up when I went over to see him the other day.
Give cya a PM and see if he can give you some clues.
Regards Rod