What year is your car and what PCM flash do you have? The miss you are experiencing upon warming up is probably a result of you having an older tune. Take it to the dealer and ask for an updated PCM flash and I'd be willing to bet that will take care of it. Or if you're looking to "upgrade", get and SCT or Diablo flasher from one of the sponsors on the site.
I drive an '04 SVT Focus. I installed the MSD Coil Pack and wires at JetFest and have been nothing but impressed with their performance. They smoothed out my idle with the A/C on and they smoothed out WOT. The car sounds and feels a little stronger on the top end also. The install was a bit of a pain due the wires not wanting to go onto the coil but once they are on they don't come off. The wires are also a little longer than the stock ones but not so long as to not fit. Good luck with your install if you decide to get these. Nate.
I agree with natedog. I felt similar gains after installing the MSD on my 02 SVT. I am not running the MSD wires though, any Ford Escort ZX2 wires will also fit perfectly. I am running Ford Racing 9mm ZX2 wires and they are also slightly longer than stock, but still fit.