I'm not sure if the Taurus used the same 3.0 V6 as the Windstar did, but if so, it's probably a headgasket. Pretty common issue, should it be the same engine. Do a compression/leakdown test and see if you can find the source, as well as a pressure test of the cooling system, if you have the equipment available.
You may still have a code stored, even though the CEL isn't illuminated, so pulling them may still be a good idea. I'm not sure what to make of the squeaking coming from the wires, aside from having a look around for anything that's loose in that area. Possible loose bellhousing bolt, maybe?