First off i would have said check the lambda (exhaust oxygen) sensor but seeing as thats been done, it leaves a few other possibilities..
When you say the car clears itself after a while.. it makes me suspect fuel rather than ignition.. i might be wrong though. I would have thought ignition problems would cause problems from the start and wouldnt clear.
If it were my car, I'd be wanting to check the operation of the fuel pump, and check if the fuel filter has been replaced. (depending on mileage)
I'd be wanting to confirm that the fuel system is getting up to pressure properly. Dont know how to go about doing it though.. (maybe a garage job)
I think faulty mass air flow sensors can cause running problems like this too, as the ECU is unable to accuratly set the correct fueling for the amount of air taken through the intake.. but i dont think the 1396cc K series engine is fitted with one.
Last edited by KSeriesMike; 28-11-2007 at 22:55.