Help everybody!

I have parked my Vanagon until you guys can give me sage advice.  I 
mentioned a few weeks ago that my van was having trouble getting gas 
while going up hill.  It all began when I let the gas tank get lower 
than usual (I try not to let it go lower than a quarter of a tank).  
Since then, it has gotten progressively worse.  I can't find a fuel 
filter anywhere in my engine and there isn't one listed for my type 
in my '81 Haynes manual (which I know isn't worth a toot anyway).   I 
am assuming that I have a fuel injector (?) and if by chance rust 
from the gas tank is the culprit, then I am going to have a bit of a 
problem, aren't I?  This vehicle was parked for about 2 years with 
minimal driving (the PO had another newer Vanagon).

What should I do?  Take it to an expensive foreign car place and have 
them charge me mega $$?  Or is this a simple repair thing that I can 
do... take off the gas tank, roll some rocks around in it, put it 
back on, clean the carborator, replace the fuel injector...!!!  : )  
I had a blown gasket replaced on the right block last November and it 
has plenty of power, just no get up and go up the hills.  

Thanks for any and all advice.  And count me in to contribute $ 
toward the new list serve.  I love this list!

Juli (not the greatest of mechanics but willing to learn)
'81 Vanagon Deluxe Camper