Courage 21 is dying on me

Kohler Courage 21 on a Husky mower, only 80hr or so on it.

Has always run perfectly. Now I'm having some pretty major issues.

Earlier this spring, started getting really loud single backfire after shutting down. Even if I bring throttle down to low for a little bit before turning key to off.

Then started having oil leak issues. One time it blew a ton of oil, from who knows where, all over the left ("driver's") side of the mower. I'd just done an oil change, so I thought, maybe I just added too much or didn't fully drain it. It was also backed up and parked on an incline with the nose down, so I switched it up for a few weekends and parked the other way. Didn't blow oil again.

Then the other day it suddenly starts hunting/cutting out. video here () I thought I was on the verge of running out of gas, so I race it to the garage before it can die and check the tank, and it's still 1/3 full. I get a little nervous because I have had oil leaks, and so I quickly check the dipstick and the oil on it is like water... it's not milky, but super, super thin. So I drain it, and wayyyyy more oil than i've ever added comes out. Like 3-4 quarts. Smells "oily", but my gut says half of it is gasoline.

So not trusting the fuel valve solenoid, I pinch off the fuel line with vice grips, put in fresh oil, and call it a weekend. A week later I fire it up, and it's still hunting/nearly cutting out, esp at low RPMs. Higher RPMs not so much for a minute or two, and then it's like it catches up with it, and the rythmic cutting out starts to occur. You can see the auto throttle lever moving back and forth and back and forth.

So i figure I'll just push mow the front, and not worry about the back this week, and my push does the same thing and dies... So i figure, bad gas. get fresh gas. Clean both carbs, replace fuel filters, push comes back to life, riding mower just as bad, if not worse. Pulled the carb again today (sometimes the second time is the charm), nothing.

I've checked to make sure that no wires were chewed through by mice (something did try to make a nest up by the flywheel), seafoamed the crap out of it twice, carb's been cleaned twice, still worried about potential gas in the oil, and I sold my truck, so it'll be a big pain to bring it to a shop.

I don't know what to do next.

Put a fuel shut off valve in the fuel line before the filter turn it off when not in use that will stop the fuel from getting in your oil. Have had a lot of probs from those carbs. Make sure your tank is clean and nothing in there blocking the fuel.

Go to http://outdoorpowerinfo.com, find your carb and clean it.
The float valve is not shutting the fuel off which flows out of the AIR VENT then down the carb throat into the cylinder past the rings & fills the sump.
You need to do 2 oil changes immediately with about 1/2hour of running between them the first can be supermarket oil if youare very short of cash.
On the second one change the filter as well.
Clean out the carb.
& check that the float cuts off the fuel before it touches the roof of the carb ( get someone to crank the engine while you hold the float up )
If it does not cut the fuel off then get a rebuild kit.

As for the fuel solenoid.
It does not cut off the fuel supply. It closes off the main jet so fuel can not go up the emulson tube. It does not stop fuel overfilling the float bowl.
before TiER I emission controls, carbs used to vent to the outside so if the float was not shutting off the fuel, fuel dribbled out of the card.
However after Tier I that was considered dangerous pollution and the bowl vent has to go into the inlet so you do not see that the bowl is overflowing till the entire contents of the fuel tank is in the sump so you then have to tip it all out and the fuel evaporates . A real clever anti pollution idea if I have ever seen one.