I may have taken some potentially bad advice a year or so ago and started running 20-50 in my 5.4 to try to quiet the cam phaser tick. Had a problem on a very cold night a few months back where the truck started running like crap after a cold start to the point where its not even driveable. Misfire codes on 2,4,6 and bank 1/2 rich. Starts fine but runs horrible. Using scanner software getting no readings from drivers side vct solenoid, changed it twice and no change. Any chance the super thick oil mixed with below freezing temps could have sludged the oil passageways to the vct solenoid? I cant seem to find a good diagram online to see exactly hoe the system works. If that is the case does anyone think an engine treatment would clear it out, or is it already too late for that?

 

un plug the vct while its running and see if you have any change. this should sent it to default position not allowing advance or retarding, 20-50 is way way to thick of an oil especially if the oil is cold change your oil asap and get 5w20 back in it and maybe you will be ok, if not you could be looking at phasers and possibly heads.. just hope you cam journals are ok..