2003 out back will not start it turns over but wont start

A clogged fuel filter may be the problem to your Subaru not starting or a fuel pump problem. The list of reasons why your Outback will not start and run goes on. A gasoline powered engine requires three main components to start and run, proper amount of fuel, oxygen and a spark.
I personally had a problem with my fuel pump not turning on and pumping the proper amount of fuel to the injectors. A fuel pump is easy to replace and remove. Do to the nature of gasoline being extremely combustible and corrosive I would HIGHLY suggest having your outback inspected buy a mechanic that is qualified to work on Subaru vehicles.
I also had a problem with the coil pack not providing enough power to the spark plugs. Replacing the coil pack is relatively easy a 10 mm socket will remove most of the bolts that will need to be removed.The coil pack essentially provides the spark for the engine to continue running. This is a part that is commonly over looked by DIY mechanics.
I did at one point have a problem with a sensor that would detecthow much oxygen the engine was using and needed. I replaced that and my Subaru ran beautiful.
If what I have mentioned above feel uncomfortable for you to replace please have a qualified person fix your Subaru with there hands.