Some weirdness at the track.

[NewArt]

Winding it out down the straight after a few laps of high rpm driving, I get a smoke bomb and a flashing CEL ! Oh dear me, says I. What could be the cause of this? Then the CEL goes out and the car continues like nothing had happened.
Cruise into the pits and hook up the Durametric: misfire code and specifically cylinder 6 misfire code ( can damage catalytic converter, it says). Clear the codes. Run some more laps, drive the next day ( slower due to wet track). Nothing. Drive home, pull #6 plug: clean and dry. Still no codes. Pull the AOS to intake plenum tube and it seems a bit oily. I am suspicious of this. So what do you think friends? Am I on the right track?