Pull the plugs one at a time and look at the tips. This will tell you if one cylinder is problematic or if it is a random condition. Random is harder to find as it can be anywhere thru the fuel delivery system, etc. A miss is a tough problem to diagnose. It can be as simple as a set of plugs, or as complex as a motor rebuild. A compression test will eliminate mechanical engine damage pretty quickly. Replacing the plugs is a cheap first attempt at a fix.2008 Pantera Classic2014 Mercury Pro XS 200
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