Ive only had my firestorm a couple of months now and ever since ive had it it has cut out now and again at traffic lights or when i put it into neutral and coast upto the lights

Sometimes when im sitting there at the lights it goes to cut out and makes a nasty clonk noise but picks up again, the tickover isnt set very low so i have ruled that out (maybe im wrong to do so?).

I did a small service when i first bought the bike, ie change oil and oil filter, but i havent changed the air filters or spark plugs, so this could possibly be the reason for this cutting out problem?
Also now and again, the bike sounds a bit rattly below 3,000 revs, as soon as it goes over 3,000 revs the noise goes, could this be CCT's? or a problem with the carbs? The bike only has just over 8,000 miles on it.
Any help or advice would be great, thanks for your time!
