May not be the same problem, because it was on an I/O, but on my old boat that would happen and it was from the clutch dogs in the lower unit getting ate up and slipping. I'm not sure if the V-Drive has anything similar to that inside of it, but it could be a worst-case scenario thing to look for. Did you check the V-drive oil to make sure it was good? It could easily be a throttle-linkage doing it too, I really doubt it's the PP solenoid. It should have a knob on it and if that knob turns smooth that shouldn't be the problem, plus it probably wouldn't hold a very consistent speed before it would throw out of gear which you would have noticed
I don't know how to "recycle" the Perfect Pass, sorry.