Airflow meter won't stop it starting. Zetecs will start and run with it unplugged.

Did you change the fuel filter when you replaced the fuel?
Pulled the injectors and given them a clean? Poor spray pattern could be a cause.
Checked the cam timing (tho I'd expect pops/bangs/or horrible engine noise if it was that out)?
Compression test? Its an unknown engine, could easily be f*cked