Flash CEL is bad, it means "warning, engine damage may occur", so just FYI.
Steady CEL means "have a look when you have time, no rush"
Flashing CEL on misfire is common and not good.
"tick" and "knock" are quite different noise wise, tick could be valve train issue.
2005 3.0l is in the range of the "recessed exhaust valve seat" issue Ford had with Rangers, 2004-2006, were the year of that TSB.
And it was misfire issue that just starts one day.
Google: TSB 05-26-3
The knock could be spun connecting rod bearing, caused by overheating because oil got low.
Oil does lube the bearings but cooling them is just as important if not more so, running low means less oil in the pan cooling off.
If you can hear the Knock at idle, then pull off spark plug wire for #5, while engine is still idling, if knock goes away then it is connecting rod bearing issue.
You should actually test all the cylinders that way.
Compression test is only way to test for the TSB issue