1993 Buick Century fuel injection

My father's biuck was run out of gasoline and has been giving us trouble ever since.
The filter has been changed, the fuel pressure has been tested at approx. 45 lbs. And there is good fuel flow when I take loose the fuel line at the filter near the tank.
I fear I may have to replace the injectors at a price I would rather not pay. Do you have any suggestions what to check before I replace them?

Thank you
Kevin