I have a 2010 aveo its been running fine until this morning it started missing and running very sluggish. I had just replaced the spark plugs about 2 months ago or so but still went in and hadx the code read. Its a misfire from cylinder 4 so I bought new plugs and replaced them still having the same issue. Not wanting to take it to a shop if I can fix it myself as my family is on a tight budget. please help. I think its the coil pack but not sure how to find out. Does the coil pack go out often on these cars I have 113,000 miles.Thanks in advance.