Buddy has a 96 with bout 300k miles been running b100 for about a month. Yesterday can only get 30mph out of it. Fresh oil and filter fresh fuel filter yesterday. B
Stock except 6637 filter. Uncheck plugs are tight have not checked fuel pressure yet. It starts ok but seems to lope at idle. My scanner is loaned out 100 miles away. Any ideas. Sorry for long post.

 

UVCH plugs. Fat fingers. Sorry.

 

I don't have anything solid for advice, but here are a few thoughts from what I've heard/read:

Biodiesel acts as a solvent for the entire fuel system. I've studied that when you run pure biodiesel, you have to watch and change your fuel filter frequently in the first few days/weeks/months because it will break up any deposits in your fuel system and pass them through, ultimately winding up in your filter. It's good that you changed it. I would check the fuel pressure to see what you are getting. I think (hopefully someone will chime in and back me up here) that it's supposed to be around 30-35 stock. Can't remember exactly.

Is this the first time you've used biodiesel? Is it a home-made brew? I talked to Jim of Rosewood Diesel about biodiesel one time, and he said that home brews can damage injectors in certain ways. Not sure how. Maybe he can chime in here.

There is also the biodiesel forum - you may want to post your question there too to see if those guys who actually run it can help. They might know right off the bat. I've never used it, but would like to make my own eventually.