There's a buffer built into the fuel level sender that is designed to dampen the movement of the needle. If the needle is jumping around, the level sender needs to be replaced. It can be serviced separately after removing the fuel pump module from the fuel tank. The easiest way to drain the tank is to drive it
the next easiest way is to remove the fuel line from the filter, attach a hose to the line, direct the line into an appropriate container, and jump the orange wire to the grey wire in the fuel pump relay socket.