The filter may very well fix it. If you have enough hose to tape your fuel pressure gauge to the windshield, drive the car around for a good while to make sure the pump gets as hot as it's going to get (not sure how long you drove it to do your test). My old pump would go for 20 minutes or so fine, then drop down to 30 or so p.s.i. and barely even run. I was used to pumps dying instantly if they were bad, so it took me a bit to figure that out.

(Edit: re-read and saw you'd already taken care of the FPR)

Once you get it sorted out, I highly recommend a 3-bar setup and more boost (and a wideband)--it's tons of fun. Here's a pic of what I've been up to this week for inspiration.