Good morning Justin, were you able to come up with a solution with your problem

Yes the plugs do need changed but do you think that would be the rough idle issue, a miss would miss at idle or full throttle, it runs rough at idle but smooth's out at 3/4-full throttle

You have to pull the plugs, no other way around it, you can either get away with just cleaning the holes with a thread chaser or like you said, helicoil, but look at it this way, if it's not the plugs, you will have to pull the head anyway cause it's probably a valve issue. Wouldn't think so at 3700 hrs, we've had some luck by slowly working the plugs in and out while soaking with penetrating fluid , getting a little at a time and thread chasing the holes, and of course applying anti seize on the new plugs,good luck

yes it does have injectors, there all new, I forgot to mention that as well as the throttle body is new

If the plugs have been in for 3700 hours they need changed. Does this engine have fuel injectors?