It won't have mice nests in it. I've had it apart and cleaned out. Throttle cable isn't loose but I'm wondering if perhaps the linkage somewhere is binding and not allowing it to govern freely. I highly doubt coil but don't have a second one to throw on and would like to be sure before buying another just to eliminate. They aren't like the single coils when you go to buy
I'm thinking of throwing a condenser on it tomorrow and checking the points again just to be sure. The Mag 18 I had in my 782 was so much easier to eliminate issues with the magneto
I'm also going to take another gander at my blue ribbon service manual and see what it has to offer. My 782 actually did have a similar issue a few years ago and it was the fuel pump, but on that one it ran perfect then 20 mins later sputtered and wouldn't even start for a while. It just wouldn't work when the motor got hot.