I am the only one here who knows what the hell is going on here?
The only way to totally clear up these issues is to rebuild the carb. I guarente you that mud/water got into the carb and is choking off passages inside the carb. I have been there several times before and adjustments will improve it i guess along with spark plugs and a new ari filter. But I highly recomend not replacing the spark plugs until you clear up the carb because all you will do is foul up a new set of plugs. Only after you got the thing running right then you replace the plugs. Believe me plugs are NOT the root of your problem only a mere symptom. Also just for your reference black smoke means running WAY rich. And someone said it before, your carb isn't supplying enough air to the engine. Make sure your choke isn't closed partially. You said that your engine reved way up and stayed there, I had the same thing happen to me, the problem was that the secondaries were stuck slightly open.
But really don't bother messing around with adjustments yet, rebuild the thing because you have dirt in there. Also once you are done replace your air filter, and then spark plugs. Also if you sucked mud into the carb, it is likely its gotten into other places too like your oil, trans, t-case, and your diffs. Check them out to make sure you don't have sludge in them.