6.4L diesel running bad

[rick105]

180,000km on truck and no issues till now,truck started to idle bad last week to the point of heavy knock and no power,turned off and restarted ran fine.Now every time I sit and idle, truck shakes with poor idle but runs fine if you just start and go.If you allow it to ruff idle for more than a minute you lose power and have to shut off and restart and go.Drive 350km nonstop on regular basis truck might chug once or twice on a hill for a second but clears up on acceleration.Slight ticking at low idle as well but disappears at 1200 rpm.also noticed trucks sitting idle is only about 600 not sure if this is right.Any ideas (injector?sensor?truck has thrown no codes or service lights.ive had all fluids and filters replaced no difference.
Truck finally through a code ,thanks for helping lol ,a number 2 misfire so need an injector