Low boost ?

[BB Wolf 63627]

My 05 6.0 has 60000 miles on it. It sits in the damp garage for weeks at a time. I have cleaned my turbo twice due to the excessive pitting on on both sides of unison ring(which I put a new one in on 2nd cleaning). Installed a new VGT solinoid, cleaned EBP sensor and tube, checked MAP sensor and tube for cracks, no exhaust leaks to be found. Still get 19 or 20 psi until shifting into 4th gear at WOT. I can get 27 on slow acceleration on interstate. Question is can a severely pitted turbo cause low boost.

[ai17828]

My 06 kept going into the dealer with a code P0299 Turbo Underboost. They cleaned and replaced the turbo a couple of times. This last time they replaced the EBP sensor valve and so far it seems to be running normal.