I had wondered if anyone else on this board had ever had to replace an engine in a '04 and up F150.
When the 5.4L started running rough with the engine lamp on I took it to my mechanic to replace the plugs. I figured at 102k that it was about time. It took quite a while to get the plugs changed [those familiar with the problem know why]. But afterwards, it still ran very rough. A compression check confirmed that the number one cylinder was “dead.”
A knowledgeable friend convinced me that we could change the engine and save a few thousand. Several times along the way I wondered about the sagacity of that decision. But now the new engine is in, and while it is slow-going [sometimes it is just too cold to work, especially after a long day] I revert to a philosophy of “one bolt at a time.”
What I found when I took off the valve cover was a spring and rocker laying out of place. What caused it to fail? I don't know. It wasn't from lack of oil change maintenance or abuse. When the spring failed the valve fell down and was struck by the piston.
I have learned a lot along the way. If anyone is faced with a similar dilemma and would like an opinion about whether to do the work themselves or have someone do it for them, please feel free to contact me.