Ya have them check the actuators cause if everything else was replace and you still have the problem you probably have a leaky actuator. If you have or can get a vacuum guage (about $60 at a auto store) you can check the actuators yourself. Hook you guage up to the large vacuum port on the actuator (after you pull the stock vacuum hose off the actuator) pump up the vacuum and see how each side holds vacuum. If one or both sides doesn't hold vacuum or it drops off more than 5 psi in a minute (ithink that's the spec if I can remeber) than it needs replaced. If your a little mechanic you might be better off checking the whole system with a guage yourself and then you will know what isa good and what isn't. But if not maybe you could be there while your mechanic does it. It really sounds like you got a vacuum leak somewhere. Good luck. Let us know if you need something else.