Could be a coil pack problem. Check at night in the dark or garage. Look for arching between 2 wire connections. Look for a carbon trail on the coil itself. (a black line like pencil mark between terminals or the case.) I read a post on here about other tests. Maybe Wiswin? or Lesabre. Either way its a cheap fix. Wouldnt hurt to do anyways. With the cowl removed and the air cleaner removed its not hard to get at. Check this site out. Not what I was looking for but it might help.
http://autorepair.about.com/cs/troub.../aa062902f.htm