I posted about this before, but have now had a chance to further get into it. I purchased this from a friends dad, who said he had it checked out by two repair shops, and both said it needs a coil. It runs very rough at low idle and fine at wide open throttle,maybe the odd sputter but, otherwise smooth. I cut my lawn with it to see if it acts differently warm, but it's the same. Does this sound like a coil problem ?