Having "Power Drop" or "Rough Running" symptoms would reek of a faulty ignition coil. Its not part of the service, but if they do fail withing your warranty, they will be replaced for free. Otherwise, its just like swapping out spark plugs, pretty easy.

Packs shouldnt cause the ESP light to come on though, but if you have a check engine light, you can get the code checked (go to an independant place and pay around $50 for this, not $150 at the dealership.