99 powerstoke low power

Hello all, I have a 99 stroke and I have been through just about everything but the right thing. I scanned the truck and came up with icp higher or lower than desired, swapped out the icp sensor with a known good sensor and no change, tested each head for oil pressure and it was ok, ipr valve works fine and I am reading good pressures. 550 at idle and up to 2800 spiked and full load, pressures change on throttle pos. When I am underway WOT 2nd gear comes in and white smoke and lack of power follow soon. Fuel pressure is good, filter is new. Can the fuel return to the tank on the 2nd Gen. trucks or is it dead headed in the heads? No other DTC's can't find the problem but it acts like a bad MAP or BARO sensor. Can the middle " O " ring leak and cause this? My fuel is also very cloudy (no water) drained and refilled with clear fuel and after 20 min. of running ( cloudy again exactly the same) can it be oil contamination? I am at a loss now, please help if possible.
Thanks Road Hazard:banghead:

I found the problem when I did a fuel pressure test and the pressure fell off at High Idle. The plastic pipe in the fuel filter housing has a check valve in it and it was stuck shut due to tampering and an " O " ring was cut allowing just enough fuel for idle and low power demands. This tube was removed and the check valve repaired and all is fine now.