Hi there, so you say you don't think it's the immobiliser that's doing it. You're gettng a spark and you're getting fuel so that is eliminated to a certain degree, are you getting a spark at the right time when the valves and piston are coming up to TDC? If you're not that means that something has jumped out of place which is going to be the crank position or cam position pick up points. Also make sure that on the ECU the female block connectors under the floor pan havn't worked their way loose. I would check to make sure it is firing at TDC, if not there's you're problem. I've owned Subaru's for the past fifteen years and own my own garage so i'm pretty certain its something to do with the cam or crank position sensor.