I am a mechanic at a aftermarket shop. I have worked on numerous Sprinters, but this one is being difficult. It sets a low boost code, if you watch the scantool actual boost always lags about 5psi below needed boost. I have checked charge air system for leaks - none. Checked injector ID numbers registered in ECM - good. I have believe it to be a Turbo problem. Reason being, If I pull the fresh inlet tube off the front of the turbo I notice oil spray while running and smoke. Also when checking the impellar I seem to get alot of up and down movement. I cant find a spec on this, and currently dont have any others in the shop to compare to, and new turbo to try is very expensive guess. Current mileage of truck is 230,00 miles. Any help would be beneficial and most appreciated.