I doubt it has anything to do with the idle but since I have a upgraded battery sitting around will changing the battery help with the idle at all? I use the a/c alot so my car doesnt idle as smooth as I want it to be at times. The battery was used on my previous car because I had a stereo system in it.

 

If the idle problem lies in the electrical system, then the battery most likely will not fix it. Look to see if the spark plugs are properly gapped and that they aren't too old. (too many miles on them) I have heard from others on the forum here that adding a grounding kit helps smooth out revs and idle....

 

I only have 800 miles on the car. I did install a grounding kit as well so I guess its normal that the engine slightly vibrates when the a/c is turned on due to the 2.0 liter engine. The thing is if the grounding kit is suppose to help then there might be a chance that a battery with better/stable amp and power could help in a way? I guess I having nothing to lose since the extra battery is just sitting there collecting dust

 

Well, unless your alternator is putting out very low output, its unlikely that your battery will make much of a difference with your idle...