Briggs Snow Engine oscillates
This is the 7.5 HP Briggs engine on a Craftsman snowblower. The choke switch is a 5 position switch (left choke to right fo run). It starts easy and runs smoothest with the in the center position. However, if I leave it in this center position, the engine almosts stalls when I engage the auger, but recovers. When I move it all the way right to the "run" position, is oscillates. In the run position, it does not stall or want to stall under load, and does run. However, it oscillates up and down.
Gas is always fresh and always has Sta-bil in it.
I have attached a video link of the oscillation: