So what would be the common cause for a sputter or two after shutting her down?
With ignition switch not the kill switch, never use that it's a bad habit for people.

 

Timing off.

 

Or she's getting an air leak, getting some detonation rattle.

 

Low octane fuel will make them diesel like that, especially in hot weather.

 

Look at the spark plugs and count the threads that are dark - 3 threads at. The bottom end is the correct heat range for your combo

too hot will cause it to re ignite the fuel still coming in //// but some ignition switches will off and on and off again as your turning it just one click

use the button if it still happens - chase the plugs

 

Carbon buildup in the engine can cause that. Don't worry, it's not preignition. If you had that, you'd have parts all over the place and shrapnel in your leg.

 

Idle could be too hi as well, combine that with carbon build up and extra heat ( check the heat range like John said..) poor fuel and it'll do it .