I have a my95 Subaru, took it out Sunday and at first all seemed ok boosted to 1.6 bar then after driving for a while the boost would fluctuate between 1 bar & 1.6 bar 1 min would give full boost next would drop then back and forth. I pulled over and stuck some carb cleaner through the boost solinoid and gave it a clean and then took it back out and still the same. But seemed to be 1 bar first and second then in 3rd and above it would be going up and down from 1 bar to 1.6 bar but seems to do it more when hot any idea what it could be I checked the vacuum hoses but there okay the car is fitted with simtek and only 2 of the ports on the solinoid are being used the bottom pipe of the solinoid is a free pipe but has always been like this any ideas as to what it could be

 

Did you connect the green plugs under the dash to put it into diagnostic mode? this operates the valve and allows a more thoroughclean