Now aren't you glad you didn't unbolt exhaust stuff and jump to conclusions as was suggested in the begining.

Always do the cheap easy maintenance things first and then work you way to more and more complex of situational problems.

The SD is getting a fuel filter change becuase its power is very sporadic and been on the low as of late. I figure 30k running bio-d, WVO, regular diesel, etc. has probably finally used up that filter.