I'm not sure if anyone has encountered this before but i thought I would pass on the information I found out just recently.
I have noticed about 3 months ago that my air to fuel ratio gauge for my turbo, started to show a bit more rich that it was when i had originally wrote my last fuel map. So thinking that it was something I had done in the fuel map programing I just re-adjusted the map, and it worked like it had before except for a bit of a rough idle in cold weather.
However just last week i threw a fuel pressure gauge on my Jeep and was shocked to find the pressure up at 73 psi, so i did a bit of diagnostic work to find the problem but found nothing. Then I looked on the web to see it anyone has had this problem before, and i did find a few write ups about the same situation. What they had found was the return line inside the take ended up touching the bottom of the tank, and thus raising the fuel pressure way up. This was due to dents in the bottom of their fuel tanks.
So I pulled my tank and found the very same problem due to a very slight dent in my fuel tank, so I did as the others had done and cut 1/2" off the return line. My fuel pressure then returned to normal.
Anyone who may be having drive-ability problems and cant find the cause may want to look into this its a simple fix, also has anyone else found this problem before