Probably the best thing to do right now is to give it a by the book tune up including setting the valves, change the fluids, and give it a tank of fresh gas. Then drive it for a while and see if it comes back to running well. Unless you have a good reason to pull the head, don't do it for the time being. Your miss could be many different things, and if it really only has 800 miles and years since the last rebuild, it is quite possible the rings are not seated and need some run time.
Keep a real close eye on your gages.....and shut it down if somehting looks wrong.