If the temps where you are is warm enough, I would add more veggie oil since a little helped it. I also heard that running bio will loosen sticky sending units.
My jumpy guage fixed when I put in about 1/4 tank of veggie to a 3/4 tank of diesel.
If you are leary of putting more veggie in the tank, you may want to try lots of atf fluid.
Good luck.

__________________
82 300D....went to MB heaven
90 350 SDL....excercising con rods