After a long drive home the other day my car vibrated under heavy load in 2nd and 3rd....4x4 so any obvious ones to check first?

I noticed that the front inner cv rubber has begun to fail so I need to rebuild that but I wondered if it could be box or diffs?

Also....a few times it seemed to almost surge under power as if boosting and then dropping but the boost gauge seemed to stay constant? I was surprised to see it hitting 1.8 bar on the t34. I have an rs500 cooler and Ahmed bajoo chip on green injectors but though this was really high? I have seen previous dyno plots of 330 and 360 bhp but thought it would run lower boost for that?

Bit of a Cossie noob so any pointers welcomed.