[Grady Clay]

Sean,

Remove the fuel level sender and inspect the bottom of the fuel tank and the fuel pick-up screen filter that is also the supply fitting for the fuel pump. Get a spare fuel level sender gasket first.
Use a wood dowel (stick) and a cotton cloth to wipe the bottom of the fuel tank and screen with.
Your symptoms certainly sound like contamination in the fuel tank.

A next step would be to drain the tank and remove the filter screen for inspection.

Where is your fuel pump – on the front suspension cross member or at the left rear torsion bar tube? Have you taken compressed air to all the hoses and tubes?

Best,
Grady