I have a 08 6.7 fire ringed head arp head studs 60hp injector nozzles s&b cold air air dog 150 fuel rail plug everything deleted with edge juice attitude cts racing. Problem is when your at half throttle or more and the truck gets to 40 mph it starts to surge and loses power but still keeps rolling smoke. I can watch my fuel pressure fall off and than jump up and down. I've been told injectors and that the ecm needs turned.

 

https://www.dieselbombers.com/6-7-li...g-problem.html

this thread discussed the exact same issue. rather than re-type everything, here's the link. hope this helps!