I have a 1999 24 valve cummins I just replaced the turbo but that didn't help but my problem is I'm losing power when I accelerate and I bbn low black smoke and my exhaust temp gauge is around 12 when I go up hill inclines or anytime I need power. I could really use some help.

have you done a boost leak test?  

 

Why did you replace the turbo?

 

What mods?

 

any codes and do you have anything to read sensor data?

Did you change the turbo specs? HX35W to something else?