I have a 97 7.3 liter diesel super duty with 463,000 miles very good condition. I replaced the entire fuel system tanks, sending unit water sep, fuel pump, all 8 injectors, hpop, ipr valve, fuel and air filter . It has a lot of power on take off but sometimes it seems like it bogs down like something is clogged up like it's starving for fuel. The rpm's will shoot up then it will shift. At around 50-60 mph it will shake then after 60 it will smooth out. It does not do it all the time. Any know what this may be. By the way fuel and oil pressure test were fine does not smoke or use oil. I have already put 15,000 grand in to truck in last 2 years.