intermittent sputter under acceleration

[Strutter]

My '88 350 TBI started sputtering under acceleration a few weeks ago. was acelerating up an on ramp and if i pushed the petal down to get up speed it would sputter. felt like a backfire without the noise. i could give it a little petal and it would not sputter. first thing that crossed my mind was fuel filter. so i changed it. it ran fine for aproximately 100 miles. then i was at a store one day and when i got in to leave it started sputtering again. so i figuered maybe the tank was so dirty that it clogged the filter again. so i changed it again. it ran fine for about another 100 miles. then today i drove it to the park to walk my dog it ran fine there. when i got back in it to leave it was sputtering again. i got it home, parked it, got my daughters car and bought another fuel filter. when i got back i was going to put it up on a ramp but it was running fine. so i took it for a little spin. ran fine.

so anyone have any ideas.