323i cyl miss codes

Have a 2000 323i, cannot clear OBD codes for cylinder missfires (P0301, P0302, P0303) and fuel management codes (P1188, P1189). 138k miles. It stumbles just slightly (5 seconds) on cold start up, but then idles smoothly. New plugs, air filter, premium fuel. Checked for vac leaks, intake track leaks. HELP!!

i have a 323ci coupe 2000 and I had a similar problem, when i reved the car i herd it misfiring so i trouble shooted the problem and it turns out it was a faulty MAF (Mass Air Flow) sensor.
i hope this helps.
Good luck