2001 Ford F-150 engine miss

You would think an engine light would come on but it did not. This has happened three other times and no engine light. What I did find today is that one coil tested poorly on the secondary side caused by corrosion around the contact/inner spring inside the plug boot. Also found a cracked plug insulator on a different cylinder. This plug was a brand new motorcraft. All this and no engine light go figure. An ohm meter test told the tale on the coil. Should be.55 on primary and 5500 on the secondary. Erratic meter readings means bad coil. Testing this at home is quite a job since accessibility to the coils is very limited, along with the plugs. But alittle patience its not to bad. My advice to anyone reading this is if you change coils change plugs also. Inspect each very closely. Use a ohm meter when coil is removed this will save time and money. I learned something all four times this has happened.