rust in the fuel line

[katana 750]

I was just wondering if somebody could help with a problem. I inhertided an 88 corolla with a carb. This car sat for maybe five years or longer with out being turned over. The car runs but it misses quite a bit. I thought it was because the gas tank was rusty and plugging the carb. At first I just run some fuel line cleaner through the system and kept changing the filter. I was always dumping orange coloured gas out, and it never got any better. I used a bigger canster filter from a boat thinking this might filter the gas a bit better. I have cleaned the carb twice each time it is full of an orange color goo that is dissolved in the gas. When the gas evaporates it leaves sort of an orange powder behind. I assumed the gas tank was completly rusty and when I changed the tank it would take care of the problem. I just changed the tank, but it wasn't that bad, it had rust particles but the gas was clean. Is it possible it could be something else? The car has olny 80 000 km on it and the fuel lines look perfect from the outside. Inside could be different.

Thanks