vague steering

Hi all HELP required . I have a t reg jimny completly standard except for 205/75/15 general grabber at3 tyres , at any spped over 45 mph the steering feels very vague I have adjusted the steering box for play ,tried all different tyre pressures , no play on any steering joints or wheels bearings .wheels balanced and wheel alignment checked. when I bought the car it steered normally and you could drive on the motorway happily at 70 mph like my previous jimny . I am at the stage were I don't no what else to look at for the problem and the car does not feel safe to drive . your thoughts please .
thanks in advance chris

What pressures in your tyres

Hi front 23 psi , rear 26 psi I have tried all manner of different pressures and its made no difference. thanks chris

Do you offroad have you bent steering drag links panhard rods
are your trackrod ends in good condition

Hi not used for serious off road just for checking sheep and light jobs on farm and everyday transport.
Cheers chris

Just musing some alternative possibilities.
So if you have checked everything for play, bent bits, alignment etc and everything looks fine, is it's possible something is actually tight or notchy?

If a part in the long list of steering components is not free to move it could prevent the self centering action of the steering geometry, this resulting in the wandering you are experiencing in a straight line.
I guess the only way to find out is separate the ball joints etc and with the wheels up in the air and move each part from lock to lock.

Another possibility is the tyres, any others you can try on the front just to eliminate? Swap rear / front and see if anything changes.

Good luck

Mike