For those of you who see the gas gage read empty when it'* full, there'* service bulletin for that. It might be posted in the techinfo section. It involves adding a 2,000 Ohm resistor across 2 wires in the wire harness on the floor near the left rear seat. I have the detailed info somewhere - if you need it, I'll look for it.
Note, however, that it only fixed the problem on my '92 for a few weeks; now it still does this every so often.
Also note that my '93 has never had this problem since I bought it 4 years ago.
'99 Bonneville SLE, white, 112,000 miles
'02 Park Avenue Ultra, white diamond pearl, 88,000 miles