Just got a used 2005 burg 400 a couple of days ago with 3200 miles on it. I noticed a low speed stumble between 200 and 3500 rpm during easy acceleration. I think it had some year old gas in it. Put 1 oz of injector cleaner to a tank of gas. I have about250 miles on it now, It is getting about 50 percent better. Any Ideas ? I plan to replace the spark plug as soon as I can figure out where it is.