Since you said that you had to bang on the gas tank, it might be the fuel pump is sticking, and going bad.
sounds Like the pickup tube in the tank is bad.
No, the sending unit only tells you how much fuel is in the tank. It has nothing to do with how the vehicle runs.
bad fuel sensor in the gas tank.
YOU HAVE TO DROP AND DRAIN THE TANK
yes
Depends on the vehicle
bad ground connection. Also the sending unit in the gas tank could be going bad.
You may have a bad ground in that case, the ground is at the top of the gas tank or the float inside the gas tank could have sunk or got stuck. Check your wires going to and from it not have a power or ground could do it as well.
Bad fuel fill.
Pump it out with a hand pump.
check for a hole in gas tank. or seal on top of gas tank or hoses going and coming from tank.