Hot engine shutdown question?
 

Sorry for the vague title, but I'm not sure how to some this up in 1 sentence. After a good run that warms up the engines and when preparing to shut down, I always rev the engines a little to clear any "stacked" fuel in the cylinders from idling. Here's my problem, I rev my port engine up to about 2500 then let it drop back down to idle and turn the key, but it sounds like 1 or 2 of the cylinders keeps firing after the ignition is off, they/it will make a coughing/firing sound 3-4 times before dying?? If I don't rev the engine it does not do this? Why is it doing this? Should I be revving the engine? And how can I fix this? This problem is new as of this weekend? Also my starboard engine all of the sudden is running rich whether hot or cold , this problem is new as of this weekend also? Where should I start troubleshooting?

Re: Hot engine shutdown question?
 

If you just want to cool, run at 1500 for a minute or two before shutdown. A momentary burst to 2500 won't do much.