1. See the little valve with the electrical connector, foam filter, and vac line? That'* the BCS (solenoid). It tells the BCA (actuator) when to dump or not. Disconnect the electrical connector and vac line from the BCS, and measure the resistance of the two pins on the BCS. Let us know what it is in ohms.
2. Remove the BCA. After the BCS is off, you can get a 10mm socket on an extension in there to remove the two bolts. You'll have to rotate the BCA around to get it out of the 'keyhole' on the bypass valve arm. Look closely, you'll see what I mean.
Push the actuator in and out. How does it feel? Does it return fully? Squirt some light oil in all ports and spread it on the shaft. Work it back and forth. Put some in the BCS ports also. Let them soak a little, rotating frequently to let the oil saturate the seals and orifices. Did the BCA fully return when you pushed the shaft in? Did you work it back and forth with oil in there to re-wet the seals?
3. While this is off, actuate the bypass valve on the SC by hand. Does it move freely? If not, lubricate that with some light penetrating oil on the front and back of the SC. You may have to oil and excercise it for a few minutes to free it up. We had a member that had to do this yesterday from abrasive debris that occurred from external polishing. He had only 3psi until he did that. Was it free? Or did it bind?
If you do all that, and put it back, and still only get 2psi, start checking for vacuum leaks on all those lines. Spraying carb cleaner on each connection point at idle should help you pinpoint the leak if you have one. Your idle will change if the carb cleaner is sucked in at a leak point.