String Trimmers

I bought my first Husqvarna( 128LD )trimmer June 2011 and was very happy with it. Used it about 6 hours last summer(1/2 acre lot). This year,I was able to use it once. Now I go to use it and it dies when I give it throttle(sometimes immediately,sometimes after a few seconds of operating speed). Seems to idle fine. Using fresh fuel(running premium,100% gas) and a new spark-plug; air-filter looks like new(except motor back-fired and melted a spot on it). Muffler is fine. I noticed that the CARBURETOR IS MADE IN CHINA. Also, why did the trimmer come with a RCJ8Y spark plug? The book says to use a RCJ6Y........I have used and abused MANY cheapo trimmers over the years,and never had problems with them like this. That's using fuel from the previous year and never changing the spark plug or air filter! A 1 yr.old piece of equipment should not be having ANY issues.