One more thought I have, is it possible the EGR system is stuck open? The EGR system should only be open between like 2l and 3k rpms or something like that, if its open before that maybe its stuck and causing it to stall? Also if it were stuck open it wouldnt cause a problem in higher rpms...just a thought...

Also maybe check for vaccum leaks/leak in the Intake manifold...

All just thoughts..