My oldest 2 are 1 year apart, and I had this problem with them for awhile, too. Then a friend of mine gave me this advice which helped a lot, even if it didn't "solve" the problem: pick your battles, and only intervene for things that are safety issues. At 13 mos, chances are your youngest could care less half the time what toy he's playing with most of the time. Don't make it a federal case if the older one takes away a toy, and the baby doesn't seem to care. Teach the 3 year old to "trade" a toy with the younger one, and usually the baby will be happy with whatever toy is in front of him. While at our age (and ability to reason) it seems "unfair" that baby is constantly having his toys taken away, in reality his attention span is barely more than that of a gnat, and he probably won't get upset if big brother takes away his ball and gives him, say, a stuffed bear. And I PROMISE you it won't "spoil" the 3 year old, either. As he gets older, and learns some impulse control, he'll stop snatching toys out of the baby's hands. Additionally, as the baby gets older, he'll learn how to fight back. Trust me -- mine are now 2 and 3, and if my DS takes something away from his sister that she really WANTS, she will go after him to get it.
Anyway, this won't solve all your problems, per se, but it will at least give you a bit more "peace" when you let some of the battles go, and focus on teaching your boys the really important lessons.