ISX 15 CM870 power loss

I have a 2003 international 9900 with a 04’ Cummins ISX CM870.Yesterday I was driving and it was starting to feel sluggish and when starting to go up a hill it was gutless even when the pedal was to the floor.The only thing that didn’t seem right at the moment was that I was not hearing the turbo spooling.After a while the power came back and I could hear the turbo spooling.I read on another forum that it could be the actuator so I disconnected the air line to it with the motor on and tried to pull the rod down and it wouldn’t budge.So I hooked up an air chuck regulated at 60psi and the rod went down a good amount but I still didn’t hear the turbo spooling which from what I read was supposed to happen unless I read it wrong.Any help would greatly be appreciated.BTW I have an inline 6 just waiting on a 6 pin because they sent me a 9 pin with it.