Poor Fuel Mileage

Ensure base timing is correct, and timing advance system is functional.
Ensure fuel system pressure is correct.
Test air conditioner switch operation.
Test airflow sensor voltage output.
Test barometric pressure sensor voltage output.
Test engine coolant temperature sensor operation.
Test idle position switch operation.
Test ignition switch operation.
Test inhibitor switch operation (A/T).
Test injector operation.
Test intake air temperature sensor operation.
Test heated oxygen sensor operation.
Test power steering oil pressure switch operation.
Test throttle position sensor operation.
Test camshaft position sensor or cylinder No. 1 sensor operation.