Alright, I'm not the man when it comes to lawn mower engine issues. I have a late 90s (99, maybe 2000) Craftsman rider with a Briggs & Stratton 20.5 Twin Cylinder Engine. It starts fine and runs good... Until you put a load on it. At that point it either dies off (if it's in higher rpms) or if it's in lower rpms it runs, but runs shitty.

My guess is that it needs some carb tuning? Maybe a rebuild?

I just bought it in spring, and when I bought it I put in two new plugs, a new fuel filter, fuel line, and I've been running premium gas in it.

Any ideas??