Why does your 2004 Ford Expedition stalls?

Answer 1

Could be a lot of things, but before you spend a lot of money, check TSB 04-14-9, or point it out to your mechanic.

Seems that in '03 and early '04 models, there was a problem with electrical cross-talk between the charging circuit and ECU sensor leads in the alternator wiring harness which sometimes causes stalling.

In my case ('04 model), I was able to fix it simply by cleaning and applying dielectric grease to a small 2-wire electrical connector in the alternator harness. Connector is located just below the battery, and was contaminated with a small amount of battery corrosion.

Long term fix is to install a new alternator wiring harness, which I assume has improved shielding, and an ECU software update.