Is all anger sin? No, but some of it is. Even God Himself has righteous anger against sin, injustice, rebellion and pettiness. Anger sometimes serves a useful purpose, so it isn't necessarily always a sin. Obviously, we're going to have adverse feelings, or God wouldn't have needed to provide the fruit of self-control. Just being tempted to do something is not sin. It's when you don't resist the temptation, but do it anyway, that it becomes sin.