Calab wrote:

Howdy!

I just received a three year old B&S 3.5 horsepower mower from a friend.
Currently, it starts easy but starts pulsing once it's been running for
a few minutes.

I've been told that the mower ran fine until it was tipped onto it's
side to be cleaned out.

....

One lesser possibility given it's not terribly old but alternative to
the governor hunting is a variable air leak--loose intake or worn
throttle shaft are most common of those.

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