99 tahoe gas needle bouncing + false reading

I have a 99 tahoe, and my gas needle bounce's and give's me a false reading. If anybody has an idea what's wrong I would appreciate the help.

Two things that it could be are, 1. the fuel level sensor in the tank is going bad. 2. the ecm need to be flashed. I have not seen a 99 do this but have seen a 01.

my 99 dose th same thing after i had fuel pump changed they took down tank again to check wires and level sensor and it still does it it is off by a 1/3 of a tank... when on E i still have 10 gallons left

My 00 Limited does this... sitting still she reads E and after using half a tank I show 3/4 of a tank.... I just refuel every 300 miles... rely on the trip odometer as my fuel gage...

im having this same problem, but on a 98 tahoe 2door, after 2 pump changes. could it be the wiring harness?
I know i had to replace the harness powering the pump.

i have a 96 doing the same thing i was told to change my sending unit that it looses contact on where the float connects to it? guess it wears out but hear its a common prob in both trucks and the suv's