well heres the p-roblem say i have a half a tank i drive up the street switching at 3,000 rpm it goes down a bit but when i hit 3.500 or 4,000 rpm my fuel guage shoots down to almaost reading empty and after a few second goes back up just a bit why is it doing this.

 

Well, my gauge is like that going up the hill. It's the gas sloshing around in the tank.

 

Your fuel will pitch under these conditions:

Ascent/Descent
Heavy Acceleration
Heavy Deceleration
Hard Cornering
Etc.

Everyone's car does it. Until you get a baffled fuel cell, it's not going to change.