running poorly, lack of power, black smoke, at higher rpm. sluggish

[kentuckycucv]

Just wanted to ad that the fuel was the main issue and clogged the fuel filter. ..2 fuel filters...A bad batch of fuel not filtered properly.... I am blending wvo with diesel and that seems to work ok but straight wvo with a little diesel runs best. I have experimented with adding regular gasoline to the wvo and too much RUG will cause surging. Air bubbles in the return line cause surging. It has been running great ever since.