Sleeper is prob right bout having a injector bad my truck did the same thing poor out white smoke but no loss of power and it didnt smoke all the time. i had two bad injectors and once they were replaced there was no more white smoke. so try checkin your injectors?

 

passed cylinder balance test runs smooth as ever guess ill see how it runs after it get new intake turbo BULLETPROOF EGR cooler and EGR valve if it still does it then ill start chasing injectors