I think I found a semi-reliable way to make sure your large ship moves where you want it to (albeit slowly of course). I was playing around last night with launching a large station into orbit and found that pressing W-A-S-D quickly before actually doing any maneuvers, AND before/after enabling or disabling ASAS, seems to 'calibrate' the controls and then they seem to respond properly. I'm quite sure it wasn't pure luck, because I played with it for quite a while and it was dead reliable, whereas before I made this discovery large ships/rockets would just spiral out of control regardless of any control input. Hope it helps!