Saturday I pulled my mower onto my lawn which is on a hill but nothing mentionable. Not the first time I have done this. Ran fine as always. About 30min later I tried to crank it after sitting and it wouldn't start. Strange, I thought since it had been sitting on the hill and my tank was down to 1/4 maybe the gas had drained from one side so I added gas. Didn't help. I was able to finally get it started but only by keeping it at half throttle. I replaced the plugs, air flter and fuel filter and now it will idle but I have to move the throttle very slow or else it will stall. At idle it sounds normal but from half-full throttle is spuddering some almost like it is starving for gas. I can't think of anything else this could be considering this issue started randomly. Does anyone have any ideas on what else I could check?