Accorind to the manual the electronics checks the fuel level every few minutes. So should not flop around. If it is sticking on 1/4 of a tank it could e the guage. Mine was sticking on 3/4 when I filled up. Then it would move once the tank droped below that mark. I pulled the dash out, pulled the glass/ plastic off and just moved with my finger. It now works correctly.
'94 ED XR8 Sprint (Manual). Vintage Windsor 302 power.
I noticed mine is empty when it's a few clicks above empty, maybe that could be a case of moving the meter with my finger too. One thing I noticed is that is does wander around about 1/8 of a tank when going up and down hills. I had a Datsun 200B and it didn't wander, the difference I reckon was that the Datto had a vertical fuel tank (it sat behind the rear seat) so didn't allow for large level variance when going up and down hills.