Astro Fuel guage dancing

2000 Astro. The fuel guage just flops around from full, to empty, sometimes to 1/4, maybe 3/4. It almost always reads empty when sitting still in park (but running). On occasion it will actually read what I think is correct. Anyone ever run into this? Could a anti-slosh thing in the tank have come loose and just floating aimlessly? Maybe it's a ground issue? Maybe it's just possessed?

I have the same problem with my fuel gauge. 3 mechanics that I have taken the van to have no clue how to fix it or where the problem comes from.

See Thread "Fuel Gage Vibrating" http://www.automotiveforums.com/vbulletin/showthread.php?t=287690&highlight=fuel (Read reply by "jringo" about checking Ground)
I have a 97 Astro w/186,000m I bought it w/140,000m, so I'm not sure if it was replaced by the previous owner!
The fuel sender in the tank wore out. It is sold only with the pump assy. I bought an OEM AC Delco because Napa told me that some aftermarket pumps made a constant vine, and had to be replaced again!
I took mine out, you have to drop the tank to do this, and I could see the wipers on the PC Board of the sender were worn and not touching the PC BD. I bent them down for a temporary fix while I looked for a replacement pump, and this worked for a while.
I got my pump on E-Bay, "Buy it now", for $160 and approx. $15 shipping. Since mine has high mileage, I didn't mind installing the new pump while it was apart because who wants to have to do it all over again if the pump dies later on!
This fixed the problem! Mine was showing empty intermittently, then eventually empty all the time. I used the trip meter for a while between fill ups, what a pain!