high temps

I cant speak to having too much fuel or too little fuel except to say that if you have all the vents shut and you are heating up too much, it would seem that you have too much fuel or a lot of air leaking into your fire box! If not enough heat and vents are closed, try opening the chimney and setting the FB vent and try again. After getting everything sealed of course.
The mods would be to use a good sealer to seal up any smoke leaks not from the chimney stack. Possibly a deflector inside the smoke chamber.. I would start with getting any leaks sealed up and build a charcoal box experiment and then move on to a deflector and then maybe some tuning plates. So the order of the mods might be a charcoal box, then heat resistant sealer, then a deflector plate, then tuning plates. Work with each step til you get it dialed in and don't try to absorb all the info on the mods. I found when I first started looking at all the mods and tricks I got a headache, Its really not that hard, I just made it that way. Outside temps as well as wind will have some affect also. Good luck!

Pellet has good advice.......... Seal all air leaks...... leave the exhaust wide open for good smoke flavor..... control the heat with the air intake...