This is on a generator. The engine has a rough idle and vibrates. Is there such a thing as "timing" on an engine like this? Would it be a carb issue? It starts right up and when I slide the lever from the choke position to run position it starts to stall out about 1/4 of the way over. When I move it back toward the choke position it regains its momentum. Any general thoughts? I can give more details if you need them, but just maybe I'm missing something obvious.