hmmmm "And I do not believe it is an issue but will add the fact that the last fill up was "mistakenly" made with biodiesel."

biod will loosen any build up in the fuel system starting all the way at the tank screen. I would be shocked if the problem is the injector pump. I've seen an IP on a 98 E300 get to about 350k miles with owner made fuel. Unfortunately, he did not have anyone in charge of QC and at 350k it would not start with engine hot. He was lucky enough to find a new, old stock Bosch injection pump. Installed and car was like brand new. Anyway, has the spin on filter been changed since biod added? How long was it run on biod? How bout the screen in the fuel line coming into the top of the spin on filter housing? Has it been pulled/inspected? Make sure the o-rings are good in this area too. I'd loosen up the lines at injectors and pump/crank till you get something out.

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Jim