Yep, it's the t-stat. It's getting lazy and not closing properly when cold. Makes for extended warmups.
Just replaced mine last week for the same issue.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
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