the gasket is dirt cheap if u can find it...around 3-4 for the v6 gasket so im guessing about the same for the zetec...i dont know about the egr passages on the zetec or if there is/are any but like geopappas said it makes a big difference to completely remove and clean the throttle body on the duratec...i used his pics when i did mine several months ago and it relieved the erradict idle and stalling out my car was having as well as getting rid of the cel i had on for maybe 5-6 months...still no problems with it and much better cold performance from the car months later

i haven't seen much posted in the way of the zetec i4, but i would remove the t/b and clean it...they tend to get really nasty on the backside...others have been able to clean theirs without removing it, but no way could i have gotten mine clean enough if i had left it on the car

99 expedition eddie bauer, 5.4 v8, k&n drop-in, 3" magnaflow catback and gas mileage that makes the contour look like a hybrid