My money is on a camshaft sensor fault due to a stretched timing chain. This was very common on the K12's for the first couple of years of production and was finally cured by fitting an uprated timing chain to all engines produced from about early to mid 2005.
Code readers are very cheap on ebay, I got one of
THESE for about £10, works great on my K12 Micra, my Saab and my daughter's P12 Primera.