Truck Repair: Fuel Gauge 2000 Silverado Ext. 4x4, fuel guage, mount brackets

Question
sorry but am I looking for a certain wire? what kind of shop can check this out. thanks van,
Followup To
Question -
Dear Van,

My fuel guage is swinging back forth from E to F,  it sometimes will read right for a few minutes when I am driving but will start acting lost again within a few minutes, it never reads right when I am in the park position!  Thanks !
Answer -
Hi Johnny,
Make sure there is a good ground connection from the engine to the body or firewall of the car.
Van

Answer
Hello Johnny,
I also had a question on a very similar vehicle from a Johnny about a temperature problem, and if they both came from you, they could possibly be related, like a instrument voltage regulator.
The wire I was talking about could be a bare braided ground strap, or cable. But it could also be a black wire, usually from the right side of the intake manifold to the firewall.
But even if that wire is there, a bad ground wire is what I would suspect first, and it could be a loose connection on the back of the instrument cluster.
There is a ground back near the fuel tank, but if that one is bad, the pump in the tank quits, as well as the engine.
But your mentioning that it works correctly in park, which makes me think that the engine movement, from the torque, is causing a connection to be made, and could easily be making a ground connection through the motor mount brackets.
Van