Is being impulsive part of having Aspergers?
I would say not, but a few web sites out there list it as one of the characteristics.
Well, I would contend that impulsive behaviour caused by Aspergers is a myth. I've had my share of people, be it co-workers or those in my personal circle, tell me (or gossipped about me) that I was impulsiveness. But, that was definitely not the case; if anything, I thought very thoroughly about what I was doing or saying or sending via email or whatever, before I actually did it.
Reflecting back, I think they perceived it this way because unlike them, I didn't intuitively grasp "the big picture" of the situation, which I would surmise is due to lack of ToM and central coherence. So they must have just assumed that because I didn't take heed of certain things right away (like they would have), that I acted impulsively. They can sense right off the bat if an action can rub somebody the wrong way, or create unnecessary friction or confusion from others, etc.
All of which to say, the "impulsive" label is really just an illusion.
Much in the same vein that we get labelled "selfish" just because we don't notice certain non-verbal cues in the environment and react accordingly.
In fact, at a previous job, they started rumours about me that I must have ADHD, because I'm impulsive and I frequently misinterpret messages from people. And to think I fought so long to get a proper diagnosis after being labelled ADHD for so long!!
Despite this, there are some times when I could be somewhat impulsive - namely, when I'm dealing with bullying or berating, it makes me feel like walking on eggshells and end up making "snap decisions". But that's due to the effects of anxiety, not Aspergers itself.