I would first replace engine coolant (drain and refill). Replace thermostat when coolant is out of system. That's about all you can do, besides pay a hefty sum of money to a mechanic for diagnostics. Thermostat opens to let fluid circulate through engine block when engine has reached optimal temperature (usually 150+ degrees F). If it is not opening, you have a big problem that will cause overheating.
probably a bad water pump................
No, it wouldn't affect the idle unless you were somehow overheating the engine.
You would need to be more specific with your question. You are not providing enough information to supply a meaningful answer.
In the engine compartment
On the EGR valve assembly.
Mercury Villager was created in 1993.
There is no such part on a Mercury Villager.
Yes.
where is the PCM located on Mercury Villager 97
where is the radiator drain plug on a mercury villager
No, only one thermostat. It does have two temperature sensors though.
mercury villager heater core 2001