2010 prostar maxxforce 13 no power/speed

There is a small hose that goes to the actuator piston at the side of the upper turbo.

 

I'm having this issue with my truck maxxforce 13. Have changed the fuel metering valve, fuel pressure sensor, both the high pressure plungers and the high pressure relief valve on the fuel rail run great for about a month and started again the other day. What else should I check?

 

What is happening? Are you getting any codes? The fuel pump you did is not a Navistar recommended procedure. It can be done, but we do not replace plungers at the dealer level. The pump needs to be properly timed and calibrated from what we are told.