What is wrong with my 2000 Lincoln Town Car when it starts then stops suddenly it will stay running if you give it the gas but will stop when you let off the gas?

What is wrong with my 2000 Lincoln Town Car when it starts then stops suddenly it will stay running if you give it the gas but will stop when you let off the gas?
This is usually caused by a bad ISC motor. The ISC motor may also be called an ISC or IAC or Idle Control or Idle motor when you ask for it at your parts counter. If they look at you like you have too many heads, try one of the other names. These mostly go bad during cold or damp weather, and where I live late December and early January tend to be times when most parts houses have a waiting list for this part.

Test 1:
Wait for car to not start. Now open the hood. Try to start the car again, and when it doesn't work, have your assistant tap the ISC motor with a small hammer or large screwdriver. If tapping the ISC motor starts the car (while cranking) you need a new one.

Test 2:
Use a scan tool to do a KOER test. If you get codes indicating difficulty controlling idle speed might need a new ISC motor. Otherwise, well, who really knows?

When replacing the ISC, first clean the throttle body with Throttle Cleaner spray and a rag, then run the engine for several seconds THEN replace the ISC motor. Note that after cleaning the throttle body, you may need to hold the gas pedal to the floor to start the car for the first time.