So it was sputering on the way out, but not on the way back home? I hate those intermittent problems.
How did you replace the fuel pump, drop the tank or cut a booby hatch?
Check for any loose wires.
Check for a pinched fuel supply hose or vent.
Check for a leaky line (especially if you cut & spliced at the sending unit).
How is the fuel filter, need replacing?
Check your fuel pressure at the rail.

 

if you bought a cardone, they are limited lifetime, so as long as its not from wear and tear it stops working, you can go and get a new opti.