M66bak

Hi everyone can anyone help?
I recently bought a erst with a 2.1 zvh and after a few teething problems (head gasket blew, faulty distributor and broken fuel relay) all was well untill recently
It has developed a another problem. Joining the motorway the other week under hard acceleration it kangarooed violently I pulled straight over and it sounded like it was missing on idle and very hesitant when revved. I called the rac when they arrived 45 minutes later the car ran sweet as a nut again 😡. I drove it twice since and it was fine, then last Sunday going for a drive it started doing it again this time I left it for an hour before re-starting it anD the problem was still there and was smoking quite badly. I towed it home but I haven't had chance to check anything although I did start it yesterday and was fine again it's really starting to piss me off has anyone got any ideas?
Sorry for going on lol