Check your PCV valve. This valve helps relieve pressure within the engine. It is usually located somewhere on the valve cover. How it works is when the pressure within the engine builds up, the valve opens to relieve some of the pressure so it does no push against internal parts which can cause gasket failure. If your PCV valve is not opening properly the first thing to go would be the vacuum hoses. Just replace the PCV valve, it is cheap and easy, good place to start.
The most common cause for a 1996 Mercury Sable not starting is a dead battery. The second most common cause for the automobile not to start is a lack of fuel.
It was the starter
This sounds more like a bad cooling fan than a vacuum problem. Insure your fans are turning and are not slipping.
A 1997 Mercury Sable came stock with size p205/65r15 tires. Taller or shorter tires will cause the speedometer to read incorrectly.
Bad plugs and wires or/and coil
Yes.
The most common cause of a dome light staying on in a Mercury Sable is electrical issues. If a fuse becomes disconnected or is loose this can cause the light to remain on. Check the dimmer switch and the plunger switches in the door jambs.
Replace your transmission pump or get a new transmission.
1999 Mercury front and humming noises can because by several things. Tire noises are the most common cause. A tire that is not wearing properly can cause a humming noise.
Lack of or absence of maintenance such as oil changes and fluid levels.
stuck closed thermeostat or blown cylinder head gasket.
Replace the spark plugs and wires. Replace the fuel filter.