my old 3 door would smoke a bit like that when it was in storage was stored at my garage that i run as a business so was started and drove out then back in at night every day so would flood all the time, i had 6 sets of plugs for it in my tool box lol
your new fuel reg could be causing it, have you checked the fuel pressure since fitting it? you might be better trailering it for a set up prior to getting it mot'd as it may not pass on emmisions. i would hate for the extra fuel to cause borewash and require a rebuild!!