I'm dealing with a 20 year old Kohler commode that periodically overflows the rim. The water level in the tank is fine. When I flush it, the flush starts "normally" but after the bowl nearly drains it starts to re-fill (like at the end of a normal flush), then drains again. This happens 3-4 times before the bowl fills normally. The line has been snaked, I've replaced the valve and flapper, and I've snaked the flush "route" in the china from the bottom up and the top down (after removing the commode from the floor. Any thoughts? I've seen the posts on a commode "wearing out" and do not have any lime buildup.
Try pushing down the tank flapper by hand as soon as you see that the toilet is going to flush normally. Not to say you need to do this forever but this will better reveal a need to check for clogs in the drain pipes or drain vent pipes.
tHE FLApper staying open and large amounts of water continuing to flow from the tank to the bowl after the flush is complete is normally just a waste of water. The bowl should be able to drain whatever the tank delivers without overflowing.
Tornado victims: Do not rush to rebuild. Take your time and look for and get a good contractor. Or consider selling the property and moving to a home that is ready to live in.