I'll try to keep this short;
A little over a year ago , I put in new AC Delco Iridium 41-103 plugs.
Not long after, the CC would stop working occasionally. My code reader gave me a P0301. Sometimes a P0300. Once in a while the CEL would light steady. Never flashing, just steady.
I thought maybe I had gotten too much dielectric grease on the plug or spring. So I removed the coil, cleaned the parts with contact cleaner, checked the plug and reassembled everything.
The CC would, occasionally kick out, but turning off the truck and restarting it would "fix" it.
Over Easter weekend we traveled to Minnesota, to visit my wife's sister.
About 4-5 times the CC quit. After the first time, I just left the code reader connected and showed my wife how to clear the codes as I drove.
I had pretty much the same problem on the way home.
A couple of days after the trip, I was driving and the CEL again lit up. It wasn't far to the house, so I just drove home, let the truck Idle and connected the code reader. P0301, again.
Parked the truck and got my tools ready while I waited for the engine to cool.
Removed the #1 coil ( I could feel the suction as I removed the coil so I knew it was on the plug correctly.)
Turned the plug over to check the tip for wear or carbon build-up. It was clean. A little dark, but nothing that should cause a miss. Less than 6k miles on the new plugs.
Started to reinstall the plug, but looked into the plug well first.
As I pulled my arm back to look in the well, I looked at the plug, (now in the install position) and the ceramic nose piece was down resting on the electrode.
The damn ceramic piece was so loose I could shake it like a maraca.
It's now been about two months since I replaced the plug and a 250 mile round trip in that time and no more problems.
In the 45 years I've been working on cars I've never had a problem like that with even a used plug. And that goes back to replacing plugs and points twice a year.
So if you have an intermittent miss you can't seem to pin down, check that.
A little over a year ago , I put in new AC Delco Iridium 41-103 plugs.
Not long after, the CC would stop working occasionally. My code reader gave me a P0301. Sometimes a P0300. Once in a while the CEL would light steady. Never flashing, just steady.
I thought maybe I had gotten too much dielectric grease on the plug or spring. So I removed the coil, cleaned the parts with contact cleaner, checked the plug and reassembled everything.
The CC would, occasionally kick out, but turning off the truck and restarting it would "fix" it.
Over Easter weekend we traveled to Minnesota, to visit my wife's sister.
About 4-5 times the CC quit. After the first time, I just left the code reader connected and showed my wife how to clear the codes as I drove.
I had pretty much the same problem on the way home.
A couple of days after the trip, I was driving and the CEL again lit up. It wasn't far to the house, so I just drove home, let the truck Idle and connected the code reader. P0301, again.
Parked the truck and got my tools ready while I waited for the engine to cool.
Removed the #1 coil ( I could feel the suction as I removed the coil so I knew it was on the plug correctly.)
Turned the plug over to check the tip for wear or carbon build-up. It was clean. A little dark, but nothing that should cause a miss. Less than 6k miles on the new plugs.
Started to reinstall the plug, but looked into the plug well first.
As I pulled my arm back to look in the well, I looked at the plug, (now in the install position) and the ceramic nose piece was down resting on the electrode.
The damn ceramic piece was so loose I could shake it like a maraca.

It's now been about two months since I replaced the plug and a 250 mile round trip in that time and no more problems.
In the 45 years I've been working on cars I've never had a problem like that with even a used plug. And that goes back to replacing plugs and points twice a year.
So if you have an intermittent miss you can't seem to pin down, check that.