My 03 F250 6.0 had been having a rpm issue as if it has a govern on it. When on the brakes trying to do a boost launch, my truck only revs to 1500 rpm. Although when off the brake it goes through the RPM’s just fine. I thought maybe fuel pressure, so I changed my fuel filters and the fuel filter cap that had a crack but wasn’t leaking. Didn’t help, I’ve recently also replaced injectors and FICM no more than 6 months ago. Buddy of mine said it sounded like a torque converter issue maybe. Myself or anyone I’ve talk to can’t wrap there head around why the truck is doing it. If you have had similar experience or more info to help please let me know.