zarfia .. shudders?

Hi,please help.Zarfia w plate,it shudders(holds back) between 20 and 40 when your idoling,it runs ok accerating,its ok on tickover,Ive had new plugs,checked the coil,cleaned the throttle body,new lander sensor,its been on the machine and came back ok,please any ideas...

bri
February 2011