The main thing was to pull the toilet. So I got my wax ring & "a no-burst braided supply line" as recommended. I got one of them "polymer braided" hoses from Home Depot. I am surprised to see the stainless steel braided hoses as I have seen what chlorine can do to stainless steel. My wife is a bit of a germaphobe & uses lots of bleach on the bathroom floor (& a whole lot of other places). Hard to believe that they are using stainless in this application.
Had to replace the guts on the water stop, 35 years old & frozen on. Pulled the toilet. Poured 5 gals of water down the hole. No problem. Damned if it ain't the toilet. Wife tells me she wants a new toilet. So this time I go to Lowe's as it was closer & they got one on sale. I get it all out of the box & take the tank off the old one & toss it, pour what water was left in the old bowl down the hole.. Then & only then do I actually LOOK up into the outlet hole on the old bowl. There, right there stuck at the outlet, is what looks like an old black flapper thing from the inside of a toilet tank. Must of been there since we moved in. Obviously, the closet auger was able to push right past it then it would re-seat itself just enough to slow the flow down to a crawl.
I decided to just go ahead with the new toilet rather than trying to get it all back into the tore up packaging & return it. I could have saved the $100 by re-installing the old throne, but what the hell, as long as my wife is happy. New toilet is not bad at all, a surprisingly good flush for a low water throne. The way the tank could rock with only the 2 bolts holding it was scary but once it filled with water it was solid.
Anyhow, thanks all for your suggestions.