Hey Josh, replying on here instead of to your message so it can be seen by more, in case it's helpful..
The shops around here were all booked for 2 months last year when I had the issue, so I took the upper engine apart myself. I found a bent push rod and an exploded lifter on cylinder 4, so I bought all new pushrods and lifters( all stock all 16) and new gaskets all around. spent a lot of time cleaning all parts inspected cam with a scope and manually rotating engine with belts, cam lobes were luckily all good( cylinder heads, combustion chambers, fuel injectors all cleaned out like new. Etc.) Got everything sparkling clean, soaked lifters in transmission fluid for a day, reinstalled everything, and installed a obd 2 plug in that does a "soft" disable on the afm system.. my truck had the issue at 315,000km. It is now at 350,000km and still running great. There is still a chance the lifters will fail without the hard delete, I know, but I am just going to keep the obd2 plugin on always ( I have heard mixed reviews on them....) and continue to change my engine oil at 50% life for the remainder of my trucks life. I bought it at 60,000km, so I don't think it owes me much money anymore, and hope for the best, I hope you figure out your truck buddy.
