I never like to throw parts at a unit in hopes of solving a problem, unless I am totally lost or have ruled out all other options. That being said, as long as you have the engine open, it would be the time to do it. Haven't looked at the cost, but it is a call you'll have to make, as you'll have to open the engine to replace them later. My guess is a bad coil, but remember, I'm not there and can only go by what you post. Wait a day or two if you can and see what the other techs around here have to say. There are a few very knowledgeable guys who may have another idea.