Im shrinking an item and get the speed and size just right so end the behaviour to carry on with the rest of the animation but as soon as the behaviour is ended the item zaps back up to its original size.
Any suggestions with this? i did see a post from 07 about this but I just couldnt understand his answer.
Mark is right, Keyframes work great for that. If you want to use a behavior to make an object Scale down and then come to a nice gentle halt, the one you are after is the "Move" behavior. Change it's Z position (in 2D) and it will give the appearance of scaling up or down. When you want it to stop end the length of the behavior.
Check out this example, this is taught in chapter 3.2 of my Moving with Motion training DVD, everything is being animated by a behavior in the video. Notice how the brown ring comes to a nice gentle stop once it scales down.