If the solenoid is blocked it will lower the boost, if there is a leak it may go higher causing the ecu to pull it back.
The hose from the solenoid that T's into the boost line has a restrictor in it. If it has been replaced that could make the boost rise too high causing the same issue. Have you changed the exhaust to 3 inch? that would cause it to run higher too.
A way around it is to trick the stock map sensor into thinking the pressure is fine, you could use a small pressure regulator if you wanted, set to 12psi, but I would be getting a better boost gauge first.