TN-ELK

Where would you go from here? Install new LP and larger lines? Or go ahead with new IP & LP? I need a plan of attack. At what point would I normally see it start to throw codes?

My 99 3500 lost boost coming home the other day. No lights came on and after about 20 minutes it came back to life and ran great the rest of the way home. Now when I start it up and take off, it has no boost in the beginnning but will gradually build up to around 10-11lbs as the truck warms up. From there it's anybody's guess as to how it will act. Going from nothing to full power again. It starts great and has yet to throw a light. I just took it to our local Napa and had them plug it in to pull the codes and it showed nothing at all. Not even in the "Stored" side. I did try the APPS reset and that seemed to make no difference. It's showing 10-11lbs fuel pressure at idle and will pull down to around 6-7 at WOT pulling 6K. My question is: why are there no codes thrown? What should my next move be? Could weak fuel pump cause this type of problem? Any and all suggestions are greatly appreciated.