Try This first
Try this before you spend a $1000 bucks. One bottle per tankful. You can find it at the Parts Shop or your local Pep Boys. Also it might be the timing.
2000 Ford 7.3 Powerstroke 4x4
2006 Mazda Tribute
1983 Black 300 D (donated to charity)
1993 Teal 300 D (160K) Sold
"I love the smell of burnt diesel fuel in the morning, it smells like ....VICTORY"