I have been having rough idle on my Evo since it is new and took it to the dealership but they told me it's fine. One guy told me he changed the ignition wire and it smothen out the roguh idle. I know some of the dealership has been recommending groung kit. Any thought or input?

 

I know some cars are more prone to it...

Not sure where your from, but changes in weather can affect idle, and so can some modifications (aftermarket filters, intakes, and BOV's are the typical bolt-ons you might experience trouble with)

Here's a few things to check (or have the dealer/mechanic check)

1) Vacuum/boost leaks in any vacuum lines, and also the Intercooler pipes (some cars are loose from the factory)
2) Have them change your plugs/wires/coils in any combination they see fit, I had a rough idle for awhile when my plugs began to get fouled in the cold weather
3) You can try a grounding kit, personally I have one on my car, but never saw any difference, I do recall just after installing them that my idle was smoother, but I can't directly attribute it to the grounding kit.

I think for many people, its probably fouled plugs, once in awhile you get cruddy gas, and your plugs are just never the same, its the first thing they should be doing for you if they can't find anything "Wrong". I changed my own plugs just after the dealership told me, "No you don't need to change them for 15k miles" after I removed them, I noticed they looked fine, but the new plugs ran alot smoother and didn't misfire under load.

 

Thanks for the input!