Tune-up?

Question

Hello my name is Shaun and i own a 1988 300zx turbo,and yesturday i let a friend give my lil lady a tune up for the first time since i bought her.now before he did the job she ran great no problems but after he did the job she did not sound right nor did she run the same,i mean when she idles the whole car rocks from side to side like i have a rocket engine in their,also she does not sound the same(her exhaust)? can you help her?