Hello and thanks for using Just Answer.I will try my best to help you with your question.
Your 2002 Grand Marquis does not have an ICM (Ignition Control Module) The PCM (Engine Computer) controls all the engine sensors and components. The best thing to do first is to check for any DTCs or codes in the PCM (Engine Computer). Do this first before replacing any parts. ANy auto parts store can do this for you for free.
Get the codes and post them on this page.
Your 2002 Grand Marquis does not have that module. Ford phased that module out in 1999.
Your PCM controls the ignition coils. Your engine has eight of them. In 1999, there was two coil packs and Ford still used spark plug wires. Ford no longer uses them with the new coil on plug ignition system.
When the vehicle stalls, we need to see if you are loosing spark or fuel to the engine. ALso see if the check engine light is on when the engine stalls and is the check engine light goes out when you try to start it.
Can you better describe "Jumping The Car".
Are you jump starting the vehicle with jumper cables from another vehicle?
Ok, that is different. Start the vehicle and check the voltage at the battery. It should be 14.5 volts.
Do this check and let me know what reading you get.
The alternator should put out 14.5 volts with the engine running.
Also have the battery properly load tested and also check the battery cables and clamps on the battery post.
The alternator can fail while the engine is running. The best way to isolate the problem, is to place a meter on the battery and measure the voltage till the engine stalls. See what the voltage is. If it drops to 12 volts or lower, replace the alternator.
But if the voltage stays above 13.5 volts, we need to look somewhere else.
Do this test and see what the voltage is when the engine stalls.
I think it could be the alternator, because you state you need to jump start the vehicle.
If you have a digital meter that reads volts, touch the battery post, black on negative and red on positive with the battery connected and see what the voltage is.