Start with checking the gap on your valves.

 

Out of my comfort zone, also every now and then it will hiccup on start, I was thinking stretched timing chain

 

You can try a new spark plug and clean the air filter but with that many miles on it and the valves have never been adjusted because it is out of your comfort zone, you better take it into the dealership to get serviced.

 

have you done anything to your exhaust,i had issues with mine backfiring when i tried a different tip as the motor requires a certain amount of back pressure