I had the same problem with a Mark 61 overheating and leaning out after 3 minutes of flight every time . I cured this by bumping up the nitro content. Nitro actually has a cooling effect on the engine. I have flown it no fewer than 15 times like this with no problems. For you guys having problems landing, this plane will fly very slowly and I have found it lands great at low speeds. It really doesn't have a bad stall characteristic at all. Just give youself plenty of elevator throw with plenty of expo and you'll have it made. I also installed a Fults dual wire nose wheel which works great. Let the plane burn off as much speed as you can in the air. Enjoy