I got this truck with 75,000 miles on it and put another 30,000 on it. It suddenly started hiccuping and would not rev over 1200 rpm. Took it to a diesel mech. and was told the EGR system was clogged. He cleaned out the EGR and DPF and the problem persisted. Mech. said it needed a new turbo. We finally found out the truck was on it's 3rd turbo already. Put new turbo in and problem remained. Took truck to dealership and they redid the cleaning process as well as completed an ECM recall regarding the regeneration function. Problem persisted. Dealership determined that the EGR valve was leaking by and malfunctioning. Said the EGR needed replacement or better yet an EGR/DPF delete. Did the whole delete and reprogrammed the ECM with a RaceMe tuner. The ECM now shows no codes and there is no check engine light but the truck still won't rev over 1200 rpm. Checked the throttle valve and it is open but still seems like there is a restriction somewhere. Truck struggles and hiccups and still won't get over 1200 rpm. Even cleaned out the intercooler which didn't seem to be clogged. I'm not a mechanic and am lost as to what to check next. Truck idles fine and everything seems good until you step on the gas. Fuel filter has also been changed. Pretty sure the dealership checked the fuel pressures and I don't a DTC on it anyway. Sure would appreciate any suggestions.