In about 60 flights I have never had a plug loosen in my 80. I'm still using the Brisk plug that came with my engine and I do have baffling. The engine never overheats. You can read the baffling article that I wrote for www.RCShowcase.com It's under their FAQ section. Over heating may be your problem

I've had the plug out several times to check for carbon build up and have found none.

Ken