My 99 Grand Marquis will start and run normally.

When driven a short distance (2 or 3 miles in city traffic) and the engine has warmed up to normal, the car will either quit running from idle (at stop light), or, not restart once engine is turned off (grocery store).

Engine cranks normally and will run momentarily at extremely low rpm.

Once engine cools down, after an hour or so, the car will again start and drive normally.

The temperature gauge reads normal and fluid levels are fine, and the Check Engine Light is not on.

Any suggestions would be appreciated.