Shaky Falcon wheel

I have had the same wheel shake with my BA Falcon as described by Wayne Lee (Carsguide 29/1/11). It would start as a tremor around 85 km/h and get violent and difficult to hold, and then it would just disappear. I tried soft braking and hard braking, nothing would fix it and it would go away for days, sometimes weeks. First, my normal garage told me I had warped discs and they replaced the discs and caliper seal kits. It was all right for some weeks, but then started again. I tried Ford, but their care factor was nil. They told me to go to my local dealer who said the rod from the brake pedal to the booster was five mm too long and to take it back my local to have the caliper seal kits replaced. They replaced the calipers, fitted and balanced new tyres, did the wheel alignment. It has not acted up for two months now, but it feels as if it is suppressed not fixed.