I Have a fault with my 2007 120bhp cdti, it judders at smack bang on 1500rpm no higher no lower slap bang on 1500revvs, it only does it intermittently, i have scoured the threads but i havent found a 120bhp with the same issue, things i have replaced are the MAF, EGR and the boost pipes (near slam panel) cleaned the MAP and cleaned my throttle body out, could anyone shed any light on this? any help would be fantastic