Ya know on many MANY of these posts I see a shotgun approach.

Do you have a shop manual? There is actually a pretty good diagnostic procedure to troubleshoot the pump.

Do you have a vacuum gauge? Even in this modern age, a test vacuum ga/ fuel pump pressure ga. is just not that expensive.

You need to suspect:

Obstructions in the line/ pickup, including old hose sucking shut, and debri or other problems in the tank/ pickup

Vent problems at the tank

The fore mentioned pinholes in hoses and tubing

A bad pump that cannot pull enough vacuum

Could even be a worn pump cam/ lobe/ pushrod/ arm