Truck doesn’t accelerate past 1500 rpms

Hello everyone. I have a 2008 freightliner Columbia Detroit 60 series 14L , the truck will sometimes not accelerate past 1500 rpms and lose power. The only way to make it stop for a few days is to do a parked regeneration. I don’t have any Regen or check engine lights on. No codes either. I believe the truck has algae in the fuel system. But why does this problem seem to be solved with a Regen but if I run it on the freeway for a couple hours with a load once I slow down or stop it will start doing it again. Would this be a dpf filter problem or a fuel system problem? Thanks for the help.

 

I’ll look into that thanks

 

I’m taking it to the mechanic today , I’ll ask him about that thanks