I am not sure of the entire problem whether it starts all the time and stalls occasionally or does it shut off as if you just turned the key off? If it is the latter, check the ignition module near the distributor. If it is running try tapping the module and if it stops, that may be your problem.
replace ignition switch
1987 Ford F350 want stay running
Probably a bad relay.
It could be your EGR valve.
A Ford 1999 Expedition engine is probably not seized if it will start and idle but will then not stay running. This could be due to a clogged fuel system, faulty injectors, faulty spark plugs or a wiring problem, or even a faulty distributor.
have you tried to change the alternator ? just a suggestion
Type your answer here... It could possibly be the ignition switch.
turn signal flasher
Check the PCV Valve in the front half way down the engine
Most likely it's the motor assembly. There is an internal switch that keeps the motor running until the wiper blades are in the "park" position. If the internal switch fails, the wiper will continue to run or will turn off wherever the blades are when you turn off the wipers. Either can happen when the wiper internal switch fails.
Can it make the vehicle kill or not stay running what does it actually do.
Check for a vacuum leak or disconnected vacuum line