1999 Sierra 2500 6.0L Troubles starting

[HavingATime]

So I have been having issues with my truck starting for some time now and I finally was able to look into it and pull some codes. I am getting P0157 (downstream oxygen sensor (right cylinder bank) low voltage), P0171 and P0174 (fuel trim lean at up stream oxygen sensor right and left bank) and then P0300 (engine misfire). I read that P0171 and P0174 were common codes for hard starting, surging (happens rarely) and a strong gas smell when having a hard time starting. I looked into them by using my vacuum gauge and it was reading a steady 15 Hg. in. So I then looked into my fuel pressure and it was 60 Psi when my fuel pump was running but then would drop down to ~53 Psi as soon as it shut off. When running it was ~50 Psi and when i shut it off the Psi would drop down to 20 Psi after about 5 minutes. I though this was a little low so I checked for leaks in the fuel lines, fuel injectors, and fuel pump module all seemed to be perfectly fine. So now I'm stumped and don't know where else to look, any suggestions?

Also the truck doesn't like to get wet, when ever I go 4x4ing and hit a puddle it won't rev up past 2000RPM but will idle perfectly fine, the problem always fixes it self when it drys out in 10 - 15 minutes

 

[HavingATime]

So I pulled my injectors out and took a closer look at them they all seem to be spraying a consistent cone of fuel and none of them leak, also cleaned my fuel pressure regulator and still has troubles starting

 

[USArmyWelch]

i cant be 100% but i was just talkin to our civilian mechanics contractors here in afgahnastan today about my 99 5.3l and common problems with gmc ford and dodges and stuff shooting the shit and he had mentioned something about that under the intake is some sort of styrofome piece to help absorb water away from the knock sensors around there and they dont like to get wet or they have starting issues so it might be something to look into and ill ask him about it tomorrow and tell him the issue your having to get a more garuntee and explaination

 

[USArmyWelch]

i checked up with him on this issue and he said it could be the foam pieces that keep water from getting to the knock sensors under the intake or it could be you fuel pressure reg. hope any of this can help i notice not alot of people reply to any feeds on this forum. good luck

 

[happy 2011]

tp help you i need to know these things.
frist look at the freeze frame and tell me what the coolant temp was and air intake temp was and how fast the tk was moving and what percent of power was being used.

All this is in the freeze frame info.

Sounds like you have a intake leak (vacuum) when the tk is cold and when warms up they seal (very comon)