6.0L fuel problem?

[rwade]

I've got a walbro universal 255 inline fuel pump on my 6.0L LS with a Russell inline fuel filter (40 micron element). When it's idling its fine when I rap it a couple times and go above about 3,000 rpm it falls on its nose and if I don't back off the throttle, it will die. I'm wondering if the filter before the pump could be restricting it as demand increases or the pump is at fault? When it's idling I hear the pump whine, but when this occurs it gets quiet, haven't had any help yet so I can see if its loosing prime or actual power to the pump. Just wanted to see if anyone else has had an experience with a set up like this.