Bubbles in Toilet

When i flush my toilet bubbles come up and it doesn't always flush all the way. Sometimes leaving paper in the bowl and other times almost overflowing. The toilet is an American Standard, 1.6gpf. What could the problem be?

Sounds like you have a partial blockage in the pipe or an obstructed trap, possibly on it's way to a full one! Sometimes there are snag points for tissue and such within the drainage. There could also be a flaw in the casting of the toilet itself or an "undesireable item" caught in the trap which could cause hangups. Try giving it a good plunge, but you may have to move to a snake. Be careful, because you can crack the bowl if you're not careful with that snake. If it happens over and over and over again, I'd recommend getting a plumber in there to actually take a look at it.