I'm having trouble diagnosing this engine. It runs rough and cuts out at cold idle at any temperature. Has a bad hesitation when throttle is applied fast or slow. The engine runs rough and has a small backfire at 25-100% throttle with the choke off. Under load the engine randomly loses power to the point it almost dies. It runs good with 1/4 choke. The spark plug next to the muffler is heavily carboned and the other looks normal, maybe a little lean. I have cleaned out the carb, and tried running with either plug wire disconnected but the engine runs worse and the rpms drop so I'm assuming it's safe to say both coils are ok, right?