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Most likely the issue is a scored fuel injector. The fact that it does not happen all the time pretty much eliminates the HP oil system, but I would check the icp and connector, I have seen some trucks were the sensors will leak after a few months of replacement, I think that there may have been some bad ones put on the market but have no documentation to back that up. What I recomend that you do is at the time it starts missing, first perform a injector electrical test to verify that there are no electrical issues then do a cylinder contribution test,and finally drive it watching cylinder balance to determine what cylinder is missing. I would not suspect valve train because once again a bad valve or seat or spring or push rod will not go bad and fix its self for a while.
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