[Homewrecker]

Mine is stable. You can see it move very, very little when you shake the car, but it's not a problem when driving. I have the same setup as you. Does your guage read correctly when the tank is full & empty? I know there are a couple different ohm senders for different guages. If your reading is off it may be the wrong sending unit (too sensitive). If not I would agree with the baffling problem in the tank.