I finally got some time to look under the vehicle and particularly at the panhard rod and the right hand side seemed to have a little movement in it when i stuck the crow bar in the space above the bush (even though it was to the correct torque).
Everything else seemed to have no movement. So I removed the wheel and tightened it up some more. It has certainly made a difference though I am still getting the speed wobbles at around 85-90 but not as bad as previously.
I was concerned that I may over-tighten the panhard rod nut/bolt if i kept going. Is this possible or should I just keep tightening until it wont move or I cant move it?

