what would make my car shut off after three or four seconds ?
It starts and idles fine for three to five
seconds than shuts off.fuel pressure seems
fine when tested with gage - 27-34 psi
bad TPS,throttle position sensor,IAC,idle air control may need cleaning,both are on throtle body.you may need to replace the fuel filter,air filter also.
it's most likely the IAC but it could also be your intake flow sensor (MAF or MAP)
+1 for idle control valve
Looking for a Used Legacy in your area?
CarGurus has 15,195 nationwide Legacy listings starting at $1,795.
Search Subaru Legacy Questions
Subaru Legacy Experts