Iv'e recently got a 94 2.2 petrol mint condition pickup, problem is it steers more or less where it wants to, have checked all the joints & nothings bent, the one thing it does have is bigger wheels off a landcruiser, 275/70/16, would this cause any problems?

Joinerman

Have you checked the steering idler arm and bushes.

All the steering joints have been closely looked at.

Have you done anything to the front suspension that might have changed the caster angle?
Bad caster will make a vehicle wander.