ANOTHER UPDATE: Now I'm trying a process of elimination to try and isolate the problem. I decided to bypass the sediment bowl and use a petcock, rubber fuel line and an in-line filter at least for now. I also put in a carb kit from McDonald Carb for good measure. I mowed today in 10 inch grass for an hour and a half with no issues, so maybe I have eliminated the problem, but it has done this before, where it will run great for an hour and then try to die out again, so we'll see.
One thing I find really aggravating is the false wall at the back of the fuel tank. It makes it hard to thoroughly clean the tank since you can't get behind it to clean.
At any rate, I'll wait until next week to mow again and see if I can get the whole property cut at once for the first time.
I guess this is what happens when you buy a tractor that used to sit in a collection and then try to make it a working tractor again.