Suffocating past half throttle.

I just inherited a JD 212 after it had been left dormant for about two years. It ran great before and cut grass and blew snow in upstate NY before hand. It takes a few turns of the key to get it started each time, but when it goes, it runs great in low throttle idle. I applied new gas to the tank after it sat forever, and bought a new battery due to corrosion, but i assume that the lengthly rest ruined the gas and fouled the plug?. Once I push the throttle past half way it suffocates itself. It idles fine before half throttle, then stalls when I push up. Also, there is oddly no oil filter? I can't find it.