AP is terrible on ashe, and starting with lifesteal is only a good idea if you are planning on autoattacking creep, which would mean you aren't getting too many last hits.

You also do not have flash which, when building a glass cannon as your build is, will get you killed in a matter of seconds, that xin charges you? jarvan ults you? you are absolutely toast

Also, you have 45% crit chance, which I do not believe warrants crit damage runes

Also, you buy boots 3000 gold into your build. At that point you are going to get clobbered by anybody with red buff that decides to chase you or any melee with gap closer/master yi

I like I think I need to get my rune page up for it and it will be awesome.