Craftsman Lawnmower (only 1 year old) Not Completely Smooth - Video Enclosed
In 2016, I put in Shell 91-octane gasoline, and started using it at the beginning of spring 2016, and it seemed to be fine. Towards the end of 2016, it started not running smoothly (power not as strong as before, and you can hear the engine running at a non-constant speed). I attributed this to the fact that the gas had been in the lawnmower for a few months (one tank of gas lasted me all season), and didn't think anything of it.
At the end of fall 2016, I burned off all the gasoline in the tank, and put the mower away for storage through the winter.
I just brought the mower back out for its first use in 2017 today. I put in fresh Esso 91-octane gasoline. It took about 10 pulls to start. After starting, it was not running smoothly (sounded like it was about to die off -- i.e. engine speed slowing down, then it would fire, and the engine would continue on again). Eventually, after letting it continue to "try" to run for a few minutes, it started running in a constant manner.
However, it still doesn't seem to be running perfectly smooth. I've attached the video here. I hear a bit of speed variation in the engine even though it's supposed to be running at a constant speed. As well, I'm hearing some slight popping sounds on a continuous basis.
Video of the lawnmower running here:
What's the reason for this? If it's a mower issue, would something like this typically be covered under warranty?