Tried it all

Ok I have 164000 on my 06 jetta and I have run into a problem and I know the awnser is infront of my face but still need help. Now that is out of the way I have an over boost problem I have a good turbo and is not sticking or clogged I have chemically cleaned it am few times in the past with
Good results. I have a boost gauge in the car and it spikes to 28psi and will stay till i let off the throttle. I have all new vacum lines. I think the actuator itself is bad but I can't tell i have unhooked the vacum to it and driven it it drives the same as with vacum . so I start the Car hook the vacum to the solenoid and it pushes the rod down then I rev the car and it pulsates. So the question I have is this when I start the car should the solenoid cycle one time down and up or just go down. Number two is for boost is the rod up or down? Third is how to test n75 can I hook 12 volts to it to cycle it to insure it works and test resistance. Thanks