I have a 07 LSJ and I’m running to a problem. Car seems to boost fine but boost gauge isn’t reading past 6 psi. It is also idling rough and rpms don’t drop when going into neutral. I sprayed all my vacuum lines and don’t seem to find the issue, I’ve replaced the boost solenoid and bypass valve and nothing has changed, it’s currently running on a pcm tune from my other cobalt since it consist of the bolt ons the pcm is tuned for, can that be causing the issue? I also think it might be that the line going to the boost gauge is leaking or not connected correctly and I need help locating it. Any help would be greatly appreciated!