I cant drive up hills?

[Copytron]

This is such a bummer. So I have a 350 and a rusty gas tank in my 70 C-10. When i give it lots of gas, it bogs down some times. Then when I back off to where I am just barely touching the accelerator it stops decelerating, but it won't pick up speed. Then i noticed it only did this when the truck is pointing up hill. It doesn't even have to be a steep hill, Just a gentle slope will do it. Anyway, I was sure it was the fuel filter so i changed it.... didn't work. Now I don't know anything about carbs but I think there is something going on in there. Do you guys agree? This is only one of many issues I am having but those are for another post. Thanks yall
j