C15 help

Appreciate it. My plan is to do full tune ASAP. But for the moment I might have to just change the turbo.

 

The thing is, I’m not 100% my turbo is the problem. That’s why I’m not sure on what to do. Is there any way of being sure? Or how long does it take for a turbo to completely fail? I’ve had a couple of mechanics check it out. But they all say “this or that”. I’ve changed pretty much any sensor that could be an issue. My CAC has no leaks. & I have no check engine light. One mechanic said fuel injectors but wasn’t sure. The truck doesn’t blow white smoke or have any sort of misfire. Just loss of power

 

Well that’s exactly why I was thinking about just changing turbo first to make sure that’s the issue.
Pyro temps are at about 700-900. I cruise around 60 mph.
I would say I noticed a little more black smoke than usual on the tip of the exhaust. But nothing crazy.
I would have to open up the exhaust side to check it out. I’m assuming the mechanics did. (Hopefully)
I would say normal slack.
Fuel pressure is good. According to mechanics.
Like you said, low gears seem fine but no power in high gears. Boost used to get to around 33 psi. Now there’s a lot of lag & psi only gets to about 22-25 on high rpms & slamming on the gas.
Idk if it’s just me but sometimes I feel the truck runs better if I turn it off then start it back up.

 

Well I guess the mechanic brainwashed me to think I need a turbo. But since I wanna do full tune, I don’t want to buy just a stock turbo.
Would that cause any other issues? Such as trouble starting, or shutting off?