Here is a related link:
http://www.rcuniverse.com/forum/m_98...tm.htm#9859862.
I have an ASP 91 that will not run right, overheats and blows plugs if run on more than 5% Nitro fuel. It is one of the original high compreresion versions, but you might try some lower nitro fuel, and check for air leaks also. Good luck.