Before tearing into it, what's the first to look at for a very rich running lawn mower?
It's a 4 year old 3.5 B&S push mower. Just a basic little mower but still too new to trash.
It just barely runs, drinks gas like crazy, and makes little difference if the air filter is on or not. Fuel is fresh, and has no butterfly style choke. It's like a stuck needle and seat.
Suggestions?

Well, since I got so many responses on this thread, (thanks, y'all), I decided to just tear into it and clean/insp evrything.
Reassemble, fresh fuel, and it purr's. Go figure.