00 supercab 7.3 auto
377000 miles
Starts great, runs great, but occasionally it will get power loss at 40-60mph, coupled with shaking and vibration. Cant put my finger on it when and how it comes about. Stepping on pedal just drones and it clears up after a mile or so and all is back to normal.

I have Diablo to read codes and sensors. No tune loaded.

Only mods are hutch, zoodad and filter.

I rebuilt fuel bowl a year ago. I use B99 and #2 diesel.Symptoms are same regardless of fuel type. No water in fuel, and fuel filter new in last 60 days.

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Went to check fuel filter, and both o-rings on it were stretched about 1 inch too big, could not reinstall them. I guess its the biodiesel 99% that did that. Wonder what other rubber fuel sustem parts might get affected? Gonna go get new fuel filter, and change oil and oil filter as well. Will report back

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New filter, new oil, full tank of #2 diesel....and it runs like new. Must have been issue with B99