Hydraulic not pneumatic
I removed that solenoid also just leaving a plug there. The only thing I can tell that I did differently is that I haven't removed the impellors from the pump yet (which shouldn't make a difference), just looped it back into the resevoir.
My steering has been fine ever since I did it up until a couple of weeks ago when the needle snapped off the speedo. Put a new cable in when putting the 25 box in on the weekend along with 280k dash and steering is back to normal.
Oh, is the HICAS unit still plugged in? it's in the boot under the parcel shelf..
All I can think of that would flip the power steering out is loss of speed signal, hicas ecu disconnected and steering angle sensor off/screwed. When I put my boss kit on I noticed steering angle sensor thingo is a pretty fragile setup..
You may have already said but, how long has it been happening for? before or after you installed lockbar?