07 impreza wagon 2.5 Wont start

[imprezawagonchica]

I need some serious help.....I just got an 07 Subaru Impreza wagon due to wrecking my Tribeca B9. It has not even been a month and already pure hell. I bought off someone a state away so no warranty. Anyways what happened at first is it threw codes po301, 303 and po420 so first I replaced both o2sensors that cleared up the po420 code. So now I have both 301 and 303 codes. So I just started small today and replaced pcv valve made sure no hoses rotted and tight. Well now it wont start the car stalls right away if i hold gas it backfires. then threw code po103 and 113 but no 301 or 303. Anyways I am clueless on what to do and why it wont even run now.I do have an ignition coil pack on its way just wanted to do this since I had the part. I tried disconnecting the MAF sensor just to see if it would atleast start but no luck. I had read another form that said to disconnect and see if any change. I really need help I have already spent $600 in other repairs to the car and I only have about $300 left to spend till I am flat broke. (Oh and MAF sensor is clean no crud)

[montana tom]

On a 2007 i'm not sure but the earlier ones if you don't connect all the air intake properly it won't run .  Triple check all your intake hoses it is easy for one to be missed.

[Gloyale]

also make sure the air filter housing is clamped correctly.  

 

IIRC on that model, the lower edge has tabs that slip into the other half.  If you don't get them clipped in correctly it makes an air leak that would act like that.

[1 Lucky Texan]

miles on car? miles since timing belt service?

 

check cam/crank timing, if it slips a few notches - you might avoid valve damage but, car may not run. misfires on one bank could also point to shifted cam timing.

 

07s probably also have the troublesome early style of DBW gas pedal, but that is sometimes gonna throw its own code.