2000 Chevy Astro. After driving my van through a heavy rain storm, I started to lose power. I parked and turned the engine off. When I started the engine again, my gas gauge jumped quickly all the way to full then settled to half-full, the correct reading.
When was the last time you changed the plugs, plug wires and fuel filter?
Plugs and wires - a couple years ago. Fuel filter - never. Could the filter affect the gauge?