Hi guys, PLEASE help me! I have an 02 zetec se fiesta, its got a de-cat exhaust and 4branch manifold, 90% of the time its running abit rough, think the standard panel air filter has been replaced with a racey 1 aswell if that would make a difference? When its revving at over 3000 - 3500 revs it runs smooth as butter, but lower revs is abit spluttery and on tick over bounces from 900 - 1000revs. I took spark plugs out and cleaned them and also put the airbox back in properly, still not a lot better, and I also unplugged mass airflow meter which made it worse so I'm assuming the meter is not at fault? Any advice would be very appreciated, its my first zetec s I'm used to having xr3i's and xr2s so not sure about diagnosing myself. Cheers for reading hope to hear from someone with some knowledge!