2004 vauxhall zafira?

hello every one i have took the egr velve off like every one said to do let it soake over nite so thismorning it is clean as new i put it back on and still havent solved the problam could eny one recomend what else to do the car seems asif the turbo is not working so its flat but i have had the turbo checked and that is fine the car is a vauxhall zafira 2.0dti 2004 reg