[xeroinfinity]

I would check for any trouble codes that might be stored.
If you get a code Post it and we'll go from thier.

Your car is OBD I , thiers a section on performing this( in the Gramnd Am section- trouble codes) its pretty easy and could give you something thats causing the trouble.

It does sound like an ignition/fuel related prob, but could also be a vacum leak on the intake, or your engine control system is malfunctioning.

Sometimes its best not to try and guess what the trouble is, you'll just waste money doing that.