Bad Gas Tank........bad

[T77911S]

i thought i was going to have to replace the fuel pump(FP), until now. i just drove down the street, pushed in the clutch braked, moderately hard, and the car cut off. it started right back up. did this about 5 times and same results. came back, jacked the rear up with it running and the higher it got the worse it ran until it cut off. i have about 2- 3 gallons in the tank, visual and milage check. my gas gage does not work so i fill up every 400 miles and i am at 350. the other day when i was looking in the tank with the pump running, i could see the return fuel filling the "resivoir" and in the center i could see the supply filter.
now i do not see the return full but i can see that there is still fuel in the resivoir, not as much. but there is some in there.
i put a big dent in the tank a few years ago when i ran over a BIG "rock". what could i have done that would make it show its tale now? i dont know what the inside of these tanks looks like.
can a tank be repaired, mine looks very good inside.

anybody got a good tank they want to sell????