Use the tire wrench to turn the screw under the small flap to the left in the floor of the cargo area.
On a 1997 Mercury Villager ( according to the Owner Guide ) the spare tire is under the back of the vehicle . There is a hex nut that has a plastic flip up cover on it in the floor of the cargo area that you use the lug wrench on to crank the spare tire down ( counterclockwise to lower the spare , keep the weight of the tire on the cable when cranking up or down so the cable does not get twisted ) and the jack is in a storage compartment that has a removable plastic panel , in the cargo area , on the passenger side
In front of the engine, down in the "V".
Down same tube that holds trans dipstick.
vacuumm leak
The alternator is mounted down low on the back side of the engine.
It's down low just to the left of the battery, it has a round bulb at the top.
Bad bearing?
The speed sensor is on the top back corner of the transmission housing. It is held down by one screw.
Your Villager has only one O2 sensor located on the front catalytic pipe before the converter. You should be able to look down between the engine and radiator and see it.
On a 1997 Mercury Sable : The jack is supposed to be with the spare tire in the trunk The spare tire is stored with the tire valve facing down and the jack is stored inside the tire rim
Remove the right wheel, then get down underneath it, remove the splash shield, back off the adjuster, remove the belt, and unbolt it.
Provides a spark for the #3 cylinder in order to burn the fuel and drive the piston down, thus providing power to that cylinder.