Your diesel could be losing power from a plugged fuel filter and/or from bad fuel. Your fuel filter should be changed every 10,000 to 15,000 miles. If you're unsure of the quality of the fuel you're getting then it's better to change it more often.
If you're having issues with lack of power with your diesel give us a call at 541-791-2886 and we'll get you back on the road again.
Happy Adventures,
Heather