fuel issue

[MilkyJoe]

Hey all.

My truck has been running great, but recently it has been saking bad and shuttering in driving range-25-60 mph.

I replaced the fuel filter and it fixed the prob for 4 days. this started about 2 months ago. I have now gone through about 20 fuel filters. I just put an inline fuel filter and took the carb filter out. worked for a day then the truck starts shaking again.

Huge misfires and acts like it is starving for fuel.

My tank is 20 gallons. But I can only use 14-15 gallons of it. when it gets to the last 5 it acts like it is out.
When I bought it in sept of 2011, I could run the full 20 gallons, and I didn't have to change the fuel filters. when I was fiddling with it yesterday, I put some of the fuel in a mason jar and it was clear, but bright orange. like orange soda?

the fuel is a day old.

No matter what filter I run now, it shakes and shimmies like crazy.

The carb is a new 4bbl q-jet, and properly tuned, as is the timing.
It is a 305 with 135K
all of the vacuum lines are fine.

Thinking the tank is contaminating the gas?
Really need help before i take it to the shop.
I will have to be using someone elses car for now until it's fixed