Engine/Transmission (1998.5 - 2002) 234,236 codes, no code w/wg off, 22psi

[LTustison]

I have certainly learned much from reading related threads, but did not find my specific problem. I have 99 2500 quad,5 sp, 3. 54, LB with utility box, 103k, had recent vp44 failure. Shop said replace transfer pump also, as metal that (probably)cut diaphram in vp44 probably came from tp. How can metal come thru fuel filter? Any way, i had these codes 234,236 before failure. they came and went several times, Then i noticed a slight reduction in power at times, mostly on hard acceleration. After pump replacement,codes came back on and generally stayed on all the time. The last few days, the decrease in power has drastically increased(less power) but only on an intermittent basis. Saturday am, I took turbo off truck to check waste gate for fouling, as that is how it seemed to be acting. I cleaned the seat and disc, checked for signs of wear in turbo and reassembled to truck. I also installed a temporary 30 psi guage to the cab so I could monitor boost. Took it out for a drive, no codes showed up and it ran great! Boost went up to 18. 5 max, as the manual said it should. the next day, the same problems were back, codes 234, 236, 237 only once. Now power is greatly decreased at times, but can return when it wants to. The power being off seems to be what you guys call "limp mode" or a decrease in fuel delivery rate. It is interesting to note that when power is off, the boost will still go up to as high as 15 psi, but at a much slower rate than when operating normally. Today, I disconnected the wastegate. WOW! I backed off when it hit 22 psi. It still went into limp mode ocasionally, but a code never recorded until iI reconnected the wastegate. Any ideas? I am thinking boost sensor. Anyone with similar conditions?