Cylinder 5 Misfire

Hi all...
i have just recently bought a c4s, it has been running fine up until this Friday... it started to be very lumpy and misfiring, so i took it to my friends who told me cylinder 5 was misfiring and probably needs a new coil..??, so he cleared all faults on the computer and since leaving the warning light hasn't come back on but the car isnt running right, now i have noticed there's a little puff noise everytime i quickly tap the accelerator... any ideas would be grateful

Regards
Paul

Have your friend put it back on the scanner. Even if you didn't get a check engine light, it would have to have thrown some codes.