RJ;

Stating your mileage improved when you changed a line and filter is the BEGINNING of an (very interesting!) INVESTGATION, but not an explanation!

You may have something else subtley(sp?) going on here, but sorry, without a plausible, detailed examination of just how the replaced filter and line caused the poor mileage, I just refuse to believe that they were the cause of the poor mileage problem...I just don't see how these components could do ANYTHING but impede fuelflow...and since your performance seems to be acceptable, that can be ruled out...OR leak it, and we covered detecting that in another post, and since you didn't report that, we can rule it out...so unless I'm missing something, were's the believable explanation?

On the other side of the mileage calculation, are you using your odometer, and how do its numbers compare to a known accurate vehicle or a map? If the accuracy of your fuelgauge is unknown (and as we know, they all seem to be more or less non-linear) it alone can't be trusted for a mileage calculation either...to be absolutely sure of your numbers, fill'er up and run the tank all the way to empty (take a reserve fuelcan along!) ...and I mean REALLY EMPTY...because you may not even want to trust this to really be the case (was it you who were "out of fuel" at half tank because of a defective in-tank fuel pickup tube?), then confirm you're truly EMPTY by pulling the sender and having a peek in the tank...lets do some objective troubleshooting (and reporting) here! Convince me!

Good Hunting!