Glad to know I'm not alone on this issue.
Like most of what I have read and searched about on this issue, the hiccuping in the idle of my 335 occurred after replacing the spark plugs at 42k miles. So far, it has been 2 months since this problem began and 3 visits to the dealership. I'm about to drop it off for the fourth time and tell them to keep the car until the problem is fixed.
Work done during every visit:
1st visit: Replace 2 fuel injectors
2nd visit: Cleaned and tested all 6 fuel injectors, checked spark plugs, and replace the valve cover (they found a hairline fracture on it and thought that was the culprit... nope)
3rd visit: The dealership had a BMW Rep from the factory come-by and look at it. The Rep stated the car has a "Defibrillation like-effect" which occurs when the idle is too low to prevent it from stalling out. The noticeable hiccup in the idling is the "Defibrillator" kicking in. Their theory was to reset the ECU, update software, and set the idle RPM at 700rpm instead of 600rpm (Note: I have a manual trans. and manual tends to idle lower than autos).
I'm not 100% sold on the "Defibrillation" theory. It sound logical but then again it can be BS.
My conclusion to their theory from the 3rd visit is the car still has the hiccups, although, it is not as noticeable due of the higher idle setting, plus the intervals between each hiccup are more apart or less frequent. I feel this only masks the problem instead of solving it.
Rwah ah ah... I just don't understand why a simple procedure like changing the spark plugs (in my case that is) would cause the car to act in such a way.
2010 335i black sapphire metallic, m sport, premium, performance kit, manual transmission