What plugs did you use? Was it doing this before the plug change? Had it scanned for codes?

There are quite a few things that can cause a rough idle. Fuel pump, fuel filter, vacuum leaks, bad gas, dirty injectors, o2 sensors going bad to name a few. Try to figure out what the exact circumstances are when your vehicle's idle is rough. Does it happen on cold starts, after the car has been parked for hours? Does it happen when you restart a warmed-up car? Does it happen all the time? Are there any odd noises? Do you see any smoke coming out? Take notes on anything that you think might help narrow things down. You will need to address each one and by process of elimination you will find the cause b