Serial 1b540866 I have been experiencing a sluggish mis while running and also showing up in a dirty prop which is normally clean running dons cocktails. Today I finally figured out it runs perfect first thing in the morning then starts running bad as the motor heats up. Any ideas what could cause this. I have ruled out coils by trouble shooting them one at a time with a new one. I'm thinking plug wire or maybe a bad plug although they are new.