Usually rough running is the tip off that a tuneup is needed. At 80K it would probably be a good idea to put in new plugs and a fuel filter.
Spark plugs aren't like a light bulb ( Good one minute and blown out the next) and gradually get tip wear. A dyno usually shows a few horsepower gain with brand new plugs. After 80K the plugs are close to failing. You might as well do them now.
If you are taking it to a mechanic make sure you are getting all 8. A lot of shops only change the plugs that show bad on the scope and that is not what you want done.