Why would a 1996 Mercury Grand Marquis not idle from a cold start?

Found the problem....I changed the Idle Air Control Valve. Thnaks to all that answered my question.

Two things I can think of:

Carbon build-up on the injectors; solution: speed on the highway (65+ MPH).

Idle is set too low; solution: find the idling screw and turn it up.

You probably have a 4.6 motor? If so you may have egr passageways plugging up. Although they usually are a problem whem warm if this is true. Next guess is a sensor such as a coolant temp sensor. It monitors the coolant temperature and tells the computer to adjust the fuel/air ratio. It feeds it more fuel when cold to warm it quicker. If the sensor is telling the computer bad info it may be starving or dumping too much fuel in. The computer controls the idle (no adjustment).

I had similar problem on a 96. I changed the air mass flow sensor and it ran like a champ. Took about 15 minutes. Very simple. Part costs about $85 remanufactured. Dealer tried to charge me about $300 to replace!!!