I had the 1926 Roadster in the driveway, car running in neutral on a slight downward grade and the car would coast then almost stop then free up and would coast then almost stop again. Seemed to do it on a regular basis like the same spot. Almost like a brake drum is out of round. Could it be the brake drum or U-Joint or bigger problems?
When it almost stops does it continue to travel straight or sort of pull to one side?
I'd jack up one side of the rear end and with the car in high slowly crank engine over and see if it binds up on one side or the other. Make sure you don't have any in/out play in axles.
Then you can move forward to u-joint and see it that's it. I'd just try to go from least invasive testing to more invasive so you take apart as little as possible.
If you drive it around and then come back to the driveway and repeat the process, does it still stop in the same spot on the driveway? If so, maybe unevenness in the driveway is causing it to stop. Another thing to check would be the position of the valve stems on the tires and see if it stops with the valve stem in the same position each time.
Then jack up both rear wheels and turn by hand. Can you feel a drag at one point on the spin? Try with each wheel separately and see if either one drags at the same point in rotation.
If it drags on rotation with wheels jacked up, could be an uneven brake drum or a wheel bolt hitting something inside the backing plate. Sometimes the axles and hubs are worn enough for the drum to hit something inside.
It seemed to pull to one side
I guess I should have done this first.
I jacked up the rear and tried to turn the wheels. It was really stiff. I disconnected the drivers rear brake rod and both wheels turned freely. I adjusted the rod and it is one click between too tight and turning free. Not a whole lot of adjustment remaining on the rod. I will try and get it out of the garage when I get the chance and see what it does. I have a couple little grandkids running around right now and want to they are everywhere :-)
Sounds like a too tight brake shoe slightly dragging in a slightly out-of-round drum.
Nothing is perfectly round. Sounds like your rear brakes need to be adjusted, as they are barely touching in one spot and not touching around the rest of the circumference of the drum.