Yeah, the ethanol gums things up and softens/rots gaskets if it is left sitting in the carburetor bowl. I tried it out, started on the third pull and ran well but when load hits it dies out. The governor seems to be working fine, but the carb just isn't supplying enough gas, I think. I'll have a real "dig" at it next week when have some time to play with it. I couldn't find any of the typical air or fuel adjustment screws on the carb. I've got to look it up online and see if there's a service manual. It's a Troy Built.
They have a "locked" adjustment screw that takes a special tool. I had the same problems with Troybuilt weedeaters so I looked it up on youtube and they've got all kind of workarounds to adjust it yourself. One just uses a bic pen lol. The mower mechanic told me it was an expensive tool but I found them on ebay for not much money. Not sure but Harbor Freight might have them. I meant to look next time I'm up that way.