I would guess that, in your case, the engine warms up and the expansion is working in your favor....for now. I have not done the job....as I have a '96...which has a different intake. I would guess, if you print out and follow the steps in this link....that you will be fine....
This is not my post...but the post of another member who did a great job of documenting his work.
http://leckemby.net/windstar/windstar01.html