Siegfried

This evening when I was going to go back home, my car didn' t start and CEL went on.
I wasn' t able to retrieve any code the CEL would'n t blink.
Everything was fine this morning I stop and start the engine 3 times during the morning until I had this problem. I notice that my car wasn' t starting as fast as usual these last days but it was still starting and running great.
I first thought it came from my main relay as I had a problem with it before (was almost sure it wasn't that as I replace it last time) but tried to remove and replug it.
I could hear my fuel pump and the clic of the main relay and it still didn' t start after ECU reset, the CEL was remaining on.
I removed the distributor cap to check if nothing was broken or burnt and check if there was spark (I used a metal part instead of the spark plug as I didn't have the key to remove one).
It made a spark and almost start so I put the plug back and tried again (the CEL went off) then it started.
I go back home and stop and restart the car without problem.

Should I replace, coil ? rotor & cap ? or the whole distributor ? Is there a way to make sure it's defective as I'm not even sure the problem was coming from this part.
I have a Prelude S with about 87 000 miles.

Siegfried

Could oil prevent my car from starting ?
There was some on the cylinder#2 spark plug, the O ring needs to be change.