I've noticed in the top and bottom 1/4 of a tank occasionally the needle will "fall" to the max or min position and just sit there for a while before returning to the correct reading. I'm guessing something along the lines of the motor in the cluster stops getting signal and gravity pulls the needle to either the max or the min position. When signal comes back the needle corrects itself. I dont think its the actual sending unit in the tank because when the needle falls to min the low fuel light does Not come on. I'm not sure how often or for how long the gauge does this, its just too darn small for me to see peripherally. Any help you guys can provide to help troubleshoot the problem would be greatly appreciated. Several people I've mentioned this to, including GM techs, just looked at me like I was crazy.