Man, I am about to the end of my toilet. We just put back an older standard toilet we got. Our old one broke and this was from a house on the street of the same vintage. It is an American Standard. The toilet will flush but, backs up once or twice and sometimes runs over. I have taken the toilet out and run a lot of water down the sewer line. I have also taken a snake and run it through the toliet even the vent pipe on the roof with no success. I am about to pull the toilet again and wash the bottom out. When I flush it, it is real slow as the water moves to the top the slowly flushes. By the time all the water is back in it look normal but when I flush again it might backup. Any ideas on what is happening..
A lot of times there is either a Q-tip OR a wire from deodorant that hangs on the side of the toilet and they fall in. using a regular snake the head is too small and ends up passing it (path of least resistance) TRY using a Drop Head Auger (WC SNAKE)
The older toilets do require a lot of volume for a proper flush so make sure the tank bulb is not dropping prematurely
You can adjust the lift rod and guide rod for a longer flushing action. These things are a real pain sometimes just hang in there .