Hi, I just put a new turbo in my truck, and all new intercooler piping. The turbo barks when letting off the throttle. No matter speed or amount of throttle. Has no power compared to what it used to, and there is a weird hissing noise on the front left of the motor. Can't find any leaks from intake, intercooler, up-pipe, down pipes. My wrench light is also on. Don't know what to do

 

Got Torque? If not get the App and a good Bluetooth adapter ASAP. We need Data to be helpful.

 

Sounds like a typical boost leak.

 

When does it hiss under load or at idle?

Probably a leaking up pipe which is the most common

and intercooler would only show signs of a leak under load/boost

 

Silly question but did you replace the turbo with a similar vgt type?
If not, you'll get those hiccups without a pressure release valve built in.
You might check to ensure the oil driven "solenoid " that open and closes those vanes is working properly.
Get some gauges on truck as recommended above to help steer you the right direction.