If you think this might be your problem, you can swap it with a pair of pliers in about 2 minutes. It is hanging on the airbox on late P80 and P2 cars just under the cold air intake, easy to reach. It is harder to check the lines as some run underneath the heat shield, intake, etc. and are hard to visualize. Also there is a 4th one from the intake plenum to the turbo that is also hard to trace but can be done by feel (and does harden and crack). It won't affect power but will affect driveability (exhaust wheel won't spool down rapidly).
It is a three-way solenoid valve and designed to fail "open" so that if it fails, it fails so that your turbo is vented to the atmosphere and thus can't damage your engine. You are then driving around with basically a normally aspirated 2.5l banger, missing about 50hp and about 90 ft-lbs of torque.