870 loses power at times.When it does it has low boost

[Redland1]

My truck is losing power randomly and when it does I can be climbing a small hill with the pedal to the floor and it will struggle to climb and I notice that the boost won’t pass 10 psi.Then on a return trip I climb the same hill when the turbo is actually boosting normal I climb the hill easily.Also been noticing at idle that the turbo hiss stops which is not normal for this truck and has always come on once the truck is aired up. Vgt box? Actuator? Turbo?