fills with water

I have a gerber toilet in one of my rental properties, it appears to be in good condition but I can hear it filling the tank periodically when it isn't even being used. I replaced the flapper thinking maybe it was leaking, still was filling periodically. I replaced the fill valve thinking...

I am renting an apartment, and intermittently the toilet won't completely flush. It usually starts occurring after a BM. I have tried adding water while flushing and that works for awhile. Eventually, when I go to flush, the water in the bowl drains almost to the bottom and makes a glugging...