spark plug gap

i replaced my plugs with a BKR7E cold grade copper plugs gapped it at .028 as the power primer suggested. also replaced leads with ble ngk's. d fresh plugs definetely got d car going a lot punchier specially at higher rpms compared to my worn out plugs which is a plus, down side is the car wouldnt stay idling on start up, i had to mess round with the idle screw to get it idling. it stays idling now but somehow still a bit rough and erattic, the exhaust sounds like its missfiring just slightly. other than idle it runs like a dream, im just wondering whether this is d trade off for running smaller gap, or maybe i have some underlying issues. i do have an aftermarket ems, do i have to set ignition timing suited to a smaller gap?

yes d one on the TB, got rid of AFM. im running 15 psi. yeah ill pull d plugs and gap it back to stock (i diddnt think that .1 of a mm would make such difference.) and see what happens. tps and base ignition was bang on last tym i checked early this year(but will check again). does playing round with d idle screw mess up tps readings? like u said its most likely the cold grade /small gap and winter combo thats doing my head in hehe
cheers

yes my ecu allows for individual coils (will get on to this later down d track) stronger ignition system can sustain/bridge wider gap at high rpms ryt? and wider gap allows for a much cleaner/complete burn?
i just realized that i gapped my plugs all wrong as i used my housmates ancient feeler gauge( it has 6 blades with values that diddnt make sense not imperial nor metric) so i assumed the blade with a number 7 was .7mm and used it. i bought a feeler gauge from super cheap today and it has both units on blades, i compared the 2 and it was way off . so im gonna pull d plugs tomoro and open it up to .7mm if that gives me trouble ill bring it back to .8mm

Win.