Check ABS sensors that lines up to ABS rings on all axles - happened to me a while back after done what you've gone through mine is R33 GTR, had same problem and somehow I decided to crawl underneath rear end for some reason I can't remember at the time (still can't remember now) and I noticed one of sensor didn't line up to ABS rings on rear left CV, pushed the CV back in the diff and problem went away.
Also, have a look at tyres and see if they all are the same, if one is slightly off, it'll do that, also happened to me.