run some diesel purge, change your fuel filters and go back to dino diesel for a couple of tanks. Sounds like a fuel problem to me too. I had one instance this past winter on the way to work where when I accelerated onto the highway everything was fine, but when it reached 70-75 mph it would go no faster. When I got to work, I opened the hood and looked at the fuel prefilter. It was all cloudy, and you could see that the fuel was thick by the way it clumped around the bubbles. It was -2F, about as cold as it ever got here last winter and hasn't happened since.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.