Phasers or VCT solenoid??
I have 07 sscrew with 5.4. 93,000 miles. At start up truck runs perfect. After 20-30 minutes of running motor will start to start running rough at low rpm. Diesel sound. I can rev up and motor clears up and idles fine. Should I replace VCT solenoids? Or phasers? Or both at one time?? Help its driving me nuts!!