Subaru stalls while driving, and idling

check your catalytic converter... it maybe full or clog..

Ever work on the motor or pay someone or just drive
until problems arise?

What about preventative maintenance,ever do any?

Spark Plugs,Wires,Fuel Filter,Air Filter,Check Fuel Pressure,anything?

Stalls when,under what conditions,at a stop light at idle

Check/Clean air idle solenoid !

Ever clean distributor rotor & cap?

Have to tell us something, so we have something to answer

Have checked the idle air control valve. If stuck closed it will not allow air to bypass the throttle therefore it will start and stall.

It sounds like your Fuel Pump is failing once it get warm.

simple test
start the engine and let idle
if idles ok , then put you foot on the brake
if it stalls ---replace the faulty brake booster
as with all faults in a cars
have the fault codes read first to avoid unnecessary waste of time and cash

its could be the fuel pump, if its going bad then it could be causing stall and a gas hose could be bad to and is only allowing a little gas to motor causing it to stall also

Try plug wires, that's about all you haven't replaced. Actually if you have an ohm meter you can test them - anything over 6k ohms per foot - REPLACE them. Also run a good fuel system cleaner through it and stay away from cheap gas.

Here is the common cause of surges, cold stalls, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours.

To correct this problem get a can of throttle valve cleaner (it is made by CRC) from the local auto parts store, spray it into the air intake of the engine until you have used about half the can, you will need to hold the idle up while you do this, it will try to stall, after this shut the engine down and disconnect the Negative (-) battery cable for 5 minutes. The intake is know clean, if you continue to have the stall out the idle speed control valve may be defective and requires replacement.

a good tune up shall solve your problem. replace the ff: spark plug. spark plug wires, air filter, fuel filter, and an oil change, good luck!

Check the oxygen sensor!!!Ask a garage to look for codes on diagnostics,good luck!