During a diagnoses of a recent problem I've been having. I found the hose from my secondary anti-afterburn valve had a burned hole underneath the hose due to the header, although there's 3 inches space between the two. The hole could not be seen from the top or bottom. Some WD-40 accidentally ran down the hose while I was searching the Carb for vaccuum leaks. My suggestion is make a heatshield to shield the #2 Anti-afterburn valve. Hope this is helpful info to save someone needless time wondering why the engines running rough.

 

You can either make a shield or get one from Mazdatrix. They are readily available.