gas gauge problem?

[Spartanzz]

Ok so after i got my vac/boost gauge installed and a new MAP sensor my MPG went up! But now my gas gauge is doing crazy stuff. Sometimes it spins around like crazy constantly then stops. Then it spins once and goes back to where it was then twitches alot. It used to hold steady and go down gradually. Now it does still go down like it kinda knows how much gas i have but since this happened after my MPG increased i would like to know how much gas i have left so i can try and find out how far i can go on a tank. So does anyone know of what can be causing this and if its easily fixable or if i have to replace the gauge?

[Donster]

There is actually a thread on Pennocks about this issue. It involves removing the sending unit from the tank and sanding the resistor that the metal piece on the float arm opposite the float slides up and down on. You can use your ohm meter to check different spots. I believe 90 ohms is full, and 0 is obviously empty.

A little tip for the issue with the gas gauge being way off.
I waited until Anne had driven a lot of the tank empty (about 3-4 gallons left in the tank).
I then went and found an empty parking lot and started driving serpentines and circles, hitting the brakes occasionally for about 3-4 minutes. This causes the floater to move up and down rapidly and it substitutes cleaning the slider portion of the floater. While this may only be a temporary fix, her gauge is now almost accurate again nonetheless.
I actually came up with this fix all on my own, as I was just too lazy at the moment to drop her tank
 
\D

[Spartanzz]

ok so its the actual sending unit/float that's the problem...over the weekend if i find a good open parking lot ill try this out.