guys i have the same problem.. except mine does it around 3000rpm..
I HAVE NO IDEA WHAT TO.. i have changed it all.. afm, plugs, all coil packs,tps,cheaked for boost leaks, had car on dyno cheked all sensors with diagnostic computer,changed timing..changed fuel filter, checked fuel pressure, restet ecu..
now what have i got left... chenge the ecu with another one?... check injectors for cracks/leaks.. and anymore than that.. ? i honestly dont know guys... hope u solve it... ive been liek this for 3 months