The greasecar manual turns out to be incorrect with regards to installation for an F250 6.9L. On one trip I noticed the power decreasing dramatically to where we couldn't get up hills over 35 miles an hour. Initially it looked like it might be the injection pump going bad, luckily I had it checked by some folks familiar with this, and they determined that the veg was being pulled solely by the IP, which is not good. So it was replumbed through the lift pump. Also, the temp sender apparently is causing blockage, so they put that back into the Veg filter housing.
I also insulated the tank, so it can keep warmer, not sure how much difference it makes, but every little thing helps.