jonny V-DUB

Hi guys need some help iv got mk3 golf 2.0L 8V AGG engine iv put in to a mk2 jetta iv got it to run but it idle rely lumpy and won't rev up with out feathering the throttle it just dies when i try to open it full when i unplug the AFM it idle fine but still won't rev up iv changed the AFM and still no change can any one HELP me please