So I am having a problem with my gas hand. It'* not reading the correct gas amount. For instance, I put fuel in my car, and my car would read the reasonable about. But while driving the hand will move or either drop. Can y'all help me please?

How quickly does the gauge move around? Does it move only with vehicle momentum, or does it wildly jump around?

It doesn't move with the vehicle momentum and it doesn't jump around wildly. It just moves back and forth. For instance, if I fill my car with gas to 3/4 and then drive for about thirty minutes, the hand will start moving between 3/4 and 1/2 and then reads 1/4 of tank of gas. Sometimes it would go all the way down to E, but I know its not empty because the gas light wouldn't have came on because I would have just filled up the car.

You may have a bad stepper motor in the instrument cluster. GM has had a lot of issues with those. The other possibility is a bad fuel level sender, but that usually causes irradic gauge movement and will set off the low fuel light as well.

If you can have it confirmed that the stepper motor is to blame, then it'* either a matter of repairing or replacing your instrument cluster.