The engine cooling fans are not functioning, low on coolant, bad thermostat,
Reasonably, the miles per gallon is 17 for the city, 24 for highway with 19 combined. This isn't that good for a car, but for a SUV it isn't bad.
Your brake booster is malfunctioning
Windshield seal? Lower door seal? Hole in floor ?
One reason a 1998 Cadillac Deville would cut off while driving could be the fuel pump or the car is out of fuel. Another reason could be the spark plugs.
a small evap leak would not cause your car to jerk.
it has something to do with the air flow more or less the vacume
Out of balance tire, bad tie rod, bad shock/strut, or bad alignment are a few options
Cause your car needs a tune up.
1998 Town Car should be 4.6 with coil over plug, why would you need firing order?
Probably not, although it could lead to other problems which would cause your car not to start.
No. A bad starter would cause the car not to start.
No, a bad crankshaft sensor would cause the car not to start and run.