I give up? What model year are well dealing with here? Don't make us out here in Internet land guess. Hard to give good help.
If you are looking for a WAG, how about did you reseal the heater water pump hose that runs through the motor valley?
2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.