turbo on 6.5

[spankydmax]

My turbo on my 6.5 was kida hit and miss while pulling my trailer it would boost and run great than smoke and drop speed rapidly I installed a boost gage and wired my waste gate shut on excel it will run up to 11psi then drop suddenly to 5psi even after the shift it will not increase until I back off the throttle and step in to it again.. Again it will quickly hit 10 and drop just as fast short period of boost under load then nothing but smoke I have also blocked the egr is the turbo failing that's my idea but would like a second opinion