A 2003 +8 will be GEMS in which both ignition and feeling are ECU controlled.
The major electronic components are normally OK , but the connections and wiring can be suspect.
Once you have checked the fuel pump is running and you have "clean" fuel, spark at the plugs , I would go through all the visible connectors in the loom, especially those to earth (ground) and I would take off all the earth connectors and clean them back to bright metal. After 6 months the corrosion should be be too bad , but it is worth a shot.
After this you might want to get any fault codes read, investigated and then cleared.
