I agree with Kristian, if you can bust a 3, you should be able to land both the backroll, and the tantrum fairly easy. I'll try 3's, and give up after a few tries, due to the sudden headache that comes along with the crash. Basically, I'm thinking you've had worse wrecks attemping the 3, than you would on simple inverts like the backroll, or the tantum... Maybe you need some better starting advice/pointers on your 1st attempts at the inverts? Why don't you try to describe an attempt from the very beginning to the crash... In the past, I've heard some really good pointers from the guys who have already replied to your problem.