From the Ford TSP (Technical Service Publication):

Possible causes:
-- Ignition System.
-- Fuel Injectors.
-- Fuel Pressure.
-- Evaporative System.
-- Canister Purge.
-- Base Engine.
-- Running out of fuel.


96 Contour SE Duratec V6 24-valve 2.5L ATX 108,000 mi. Replaced: crankshaft w/ DMD, EGR valve (clogged), EVR, DPFE, PCV valve, evap emissions hose & tube (cracked), window regulator (broken), LH & RH PCV tubes, UIM gasket (leak), ignition coil