As I read through this I start wondering if my newly installed Ford reman'd 5.4 with a from the first start up noticeable vibration couldn't be something extremely simple. I suspect an internal problem missed during the rebuild process. This engine was purchased from a Ford dealership so does have a 3 year 100K mile warranty so I'm not too concerned I'll be out any more significant money.
So this week it'll be back in for a compression test to verify or dismiss a suspected internal issue. I really wish a DTC was triggered regardless what it signified-----it's be so much easier to find and fix.
All this is to say I completely understand Larrie's frustration with himself for temporarily ignoring something that could have been addressed more quickly---its too easy to "get inside our own heads............." when we're even a bit mechanically inclined or experienced. We say to ourselves "it just can't be that simple.........." and yet sometimes it really, really is.
As for eliminating vehicle ownership simply because it will eventually need some sort of repair seems silly. Not really sure how renting something that's the same as what we might own is a cure---as already mentioned a vehicle could develop mechanical issues regardless who owns it and it still falls upon the driver to deal with it.
BTW Larrie---glad your issue was relatively simple to fix---thanks for your experience and sharing of advice.