WARNING: This page is about a different car, the 2003 Ford Windstar. However, it is still accessible from the selected car via links, so may be relevant.
Special Tool(s)
Fig 1: Identifying Special Tool(s)
Courtesy of FORD MOTOR CO.
Place a straight edge across the exhaust manifold flanges and check for warping with a feeler gauge.
Fig 2: Placing A Straight Edge Across Exhaust Manifold Flanges