2005 volvo with isx air loss problem

Losing Air and cant find it where, I did listen and spray soap water for every fitting I could reach, no luck so far.
I start it, and expected to fill the air tanks as usualy, but it will not fill up more than 60psi and that is idling about 700rpm. Now if I crank it up to 1200-1400rpm then it will fill up all the way to 140. here is the drama though if I dont start moving and I let it idle it will drop down below 60 and then build back up to 60-65 where the alarm goes off
Dryer is new or at least looks like new I only had this truck now couple weeks'

 

Yes I am about to replace the governor and see what happens to day.
I also had other problem but I beleive I know what it was now. You see after the second load I put on this thing I lost power averaged fuel miles dropped down to 4mpg and had all kind of codes, and the engine runs smooth not rough after all that crap.
well I started with the fuel/ fuel tank/ fuel lines/ and changed filters, nothing happen still no power, the only time she will go more than 20 mph is down hill, then changed exhaust gas presure test checked CAC. Checked the air intakes for leaks and come up with nothing hhmmm well finally I unplugged the #### egr and walaa the #### thing is back to life. And she can pull 45000lbs from 0mph to 65-70mph in a minute, as far as the fuel goes it is stuck to 5.5mph. I am not sure but I am suspecting all these have some thing to do with electric specialy Ground problem. This is the second week I have this volvo with isx so my experience is limited. And I am not a mechanic but being around trucks and owned and love the challenge

 

Well I bet there is someone out there being on this boat who figure out how to beat the #### thing. Every problem has a solution that is my task.

 

Well I replaced the air governor and nothing change. But I noticed the air loss only happens when the engine is idling on the front tank, so the question is what is connected to it that uses air only when the engine is running? Ahaa I think it must be something with the turbo may be the turbo actuator What you all thing about that now?

 

Thank you Pablo. I will just do that and report back