hi guys ive got a similar problem on a 1.8 zetec , it stutters at low revs in 4th and 5th gear , ive just checked some pipe at the back of the engine which isn't split but when I start the engine it sucks in , its the corner bit with the metal part on , so im assuming its the same part as mentioned above , when I find the part and fit it ill let you no if it solved my problem .
thanks