There is a plastic engine cover that needs to be removed to see engine, the front 3 coils/plugs are easy to see and replace, the back 3 can be removed without pulling the intake manifold but some people remove it to open up some space. The other method to get the back 3 cylinders would require removing the wiring/junction box. Honestly if you don't do these types of repairs, you either need to do a bunch of reading, get a manual too or have someone or shop do it for you.
127k miles, the plugs might have been changed but I would assume not at this point and they need to be changed too, I'd still think you have might have one coil on #3 going bad too.
127k miles, the plugs might have been changed but I would assume not at this point and they need to be changed too, I'd still think you have might have one coil on #3 going bad too.