thats exactly what my car is doing right now
it did it when i had my old 2 litre in it and i swapped in a neo and it still does it
the only things that are the same are the fuel pump,which i changed,the boost controller which i am changing tomorrow,and the maf.
so my guess is that the boost controller or the afm is not working properly,because it only happens under boost.
so try checking the boost controller and the maf
i will update if this thread when i figure the problem out,but i am fairly certain it is my old shitty manual boost controller sticking.
cheers!