shoot! Guess I forgot to hit SEND.

In short:
Yeah, all that bouncing around 4wheelin' fun probably stirred up the sediment in the tank.
Hopefully the filter is just plugged. Symtoms persist? flip up the back seats and tada, access panel for the fuel pump. Pull that puppy out and check it out. Sock OK? Rust in the pump? get a new pump maybe.

After that, drop the tank and clean it. first, try to take it to a radiator shop to be hot tanked. Less cost, WAY more work and HUGE MESS = DIY cleaning. We're talking harsh acid and a biological product called "Marine Clean."
after you get the goo, varish, and rust out of the tank, try coating the inside with tank sealer. Careful, cheap stuff or bad prep and the stuff peals or flakes off which plugs up the sock on the fuel pump. Best stuff is the POR product.

http://www.ratwell.com/technical/FuelTankRestoration.html

has a GREAT write-up on how to do it.
Why do I know this stuff? I have an MR2 that sat for 3 years with fuel in it. Sludged the tank which plugged the fuel pump. HAVE TO drop the tank to fix. <img src="/forums/images/graemlins/frown.gif" alt="" />

good luck and "Acid to water, that's how you aughter."
-Leinies