06 Cummins with 150k miles started with extended crank but started, this lasted few days. Replaced fuel filter added some fuel treatment to tank and it didnt change anything. Now extended crank and no start with no codes so I unplugged intake heater and fogged intake and fired right up, runs great cant tell anythig is wrong driving it temps and pressures are good powers and towing is all good lift pump is working. Dropped off to dealer diesel mech. and they all said injector so I replace injectors and tubes, fuel control actuator and cascading overflow valve and no change. Trucks been down 3weeks now and dealers is even scratching. Any suggestions, is it my CP3