The most common thing to cause a car or truck to stall at idling is the ignition control module that is inside the distributor for vehicles with distributors and under some coils in some models of vehicles.
The ignition coil or ignition coils could also be a cause of an engine stalling at idle but I would first check the ignition control module.
The ignition control module controls the ignition coil and spark plugs and if the ignition control module completely fails your car will completely stall and not start again eventually.
An ignition control module can partially fail and provide just enough power to get the engine started but not provide enough power to keep the engine running.
A bad distributor rotor or cap can also cause the engine to stall at idle or even a bad ignition coil or ignition coils.
Also low fuel pressure can be another cause of an engine stalling at idle.
It's hard to say exactly what would be causing your car to stall when idling unless I was there to see and test the car.
I would take the vehicle to a mechanic who can do some diagnostic tests to find out the exact cause.
Your fuel filter or fuel pump could also be a culprit but I would bet on the ignition control module going bad as that is usually what happens to vehicles that are stalling at idle when they're brought to me.
I usually put on a new ignition control module after testing it and it does usually fix the problem and helps the vehicle stay running.
The ignition control module controls the timing as well so you have to have a good ignition control module for your cars engine to stay idling and start up.