toro 7.25 190cc starts but has no power

I have a 22 walk your pace guaranteed to start Toro that has no power. It's 2012 that's only been used about three or four times, mostly last fall. I'm pretty sure I put StaBil in it in th fall. I cut the grass last week, worked fine. Cut half the yard this morning, ran fine. Filled gas tank this afternoon and it started the second pull but hunted and as soon as I tried to pull the lever for it to go it wanted to stall. after it warmed up it wasn't much better but would cut ligth grass but heavier gas would stall it again. Is there something electronic to do with the guaranteed to start system or is this another case of dirty carb already? TIA