It's a 12.7 Series 60 motor.....

OK, I had a shop adjust the overhead on my trcuk. After they did that, it started idling a bit rough and would occasionally stutter and blow white smoke. It also is a tad and is difficult to start some days smoking a bit as well then too.

My 1st thought was a bad injector or they adjusted it out of spec so i took it to the detroit dealr and they ran it on the computer. Said all the injectors were fine and operating as they should? But did state the turbo is only pumping about 18lbs boost (should be about 28?) so they said it's starting to go bad.

The motor was rebuilt by Freightliner back in 2004 and they replaced the turbo at the same time, and it only has about 300K miles on it now, why would this be going bad? The turbo is about $750 alone, not to mention labor, but I can chage this at home, just do you really think it's the turbo causing the problem?
The 1st motor was rebuilt because one of the injectors was sucked into the motor so they did a low-nox rebuild on it replacing the injector, turbo, charge air cooler, ect ect.....