Fiat Punto Ignition Leads Problems

Hi there some help is needed here, Recently i suffered with problems starting the car and i was advised by the AA to change the spark plugs to which i did however as soon as the spark plugs were changed i had a engine management light come ...

I have a fiat punto 1.2 2005 8v model yeah it is my first car but since a month or so now i have this problem where if the car is on idle the revs drop and bounce back up and the car makes a weird noise. and i think its due to this that my ...