Got a fuel filter question:

I changed both my fuel filters, the one before the fuel pump, and the one
after the fuel pump for P.M. work. There was nothing wrong with them.
Thought it was a just good insurance, and Vanagon tanks are known for
their rust problems.

Going down the road, 1000 miles later after the change, the van runs
sluggish, no power climbing the hills. So I pull over, thinking I have
fuel problem. I have spare filters, so I change the first filter, take it
for it a spin, it runs just a little bit better, but not much or  for that
matter enough to count.

So I crawl under it again in the rain, and change the other filter, it
runs like new , and I complete my travels.

I have an in-line fuel gauge that reads 50 PSI at idle, and 40-45 PSI at
full throttle, the gauge is right after the last fuel filter.

So what gives, did I just get a lemon for filter. If I have rust problems,
why didn�t the first filter clog up first?

Mark