97 Legacy Outback 2.5 Starts instantly runs several seconds,and dies. Key is still on, turn it starts instantly runs a few seconds and dies..repeat. Already replaced the fuel pump and filter. Ideas ? 

Our 95 and 97 EJ2.2 will do exactly the same thing when the MAF sensor is bad. Happened a couple of times.

Get one from a yard. The last ones I pulled myself cost me $25.00 a peace.

Turned out to be a faulty dealer installed keyless entry / anti theft system. Once I disconnected it and reconnected the cut and patched in wires in the original wiring, it starts and runs great.

Darn electronics.

Glad you got it working.

The Subaru ones are usually pretty good.  It's the aftermarket ones I always pull out.

Had a similar problem with my previous Forester. The IAC was the culprit.