hows the engine idling in park?
had a similar experience when the plugs went bad, then the coil packs one month later and just recently 1 coil pack again less than 1 year after all that.
in the early stages before the engine light came on, the engine would drive and idle normally, and every now and then it would make a strange noise or hesitate to accelerate when i pressed the gas. the delay in acceleration became more prominent as it took more time for kickdown, till eventually one morning there was no kickdown at all.... car struggled to reach 80 km/h and then the engine light came on.
similar situation recently too.. the engine light didn't come on until there was blantant misfiring, bucking and serious vibrating of the car at low rpms. one coil pack had to be replaced.