Are you sure the LSPV is working correctly? How did you test it?

How I tested mine is to jack up the rear by the differential, put the trans in neutral, spin the rear tires by hand, stomp on the brake pedal. Rear tires should stop immediately. If they don't, the LSPV isn't working and needs to be bled out. Most likely the bleeder valve is gunked up and needs to be cleaned out before bleeding the system. <img src="/forums/images/graemlins/wink.gif" alt="" />

Here's what a LSPV looks like torn down...
http://www.youtube.com/watch?v=pgYchFnp-vY

I've been told there is a valve in the brake line splitter...but I haven't confirmed it.

I would still pull the rubber lines and inspect them. You never know as you may have gotten a bad batch. Have you tried blowing out the lines completely of fluid/debris? Make sure you put a jar to capture any fluid so you can inspect it fer possible evidence. <img src="/forums/images/graemlins/wink.gif" alt="" />