Hi do you mean you have changed the VNT actuator on the side of the engine
above the starter motor,,
YOU NEED TO CLEAN THE VNT NOZZELS RING INSIDE THE TURBO,
YOU COULD TRY REMOVING THE DOWN PIPE FROM THE TURBO AND AND SPRAY TURBO, EGR, CARB CLEANER and leave over night ,
you can try some Turbo vnt cleaner that you put in the fuel tank, the in 4th gear from 40mph put your foot down all of the way and let the car go as fast as is safe then let the cr slow to 40 again do this many times to get the vnt vanes in the turbo moving,
also get some of this and run it in 1/4 of a tank of fuel,
http://www.ebay.co.uk/itm/Liqui-Moly...53.m2749.l2649
Dave