I'm pretty sure the fresh air is a combination of adding o2 to aid the burning efficiency and to cool the cat since rotaries burn hotter.

 

I'll look in to it after I get these other issues sorted out

 

try checking your spark plug leads, i had a problem with one of mine once spark was jumping/shorting thru plug lead boot and wasn't firing the spark plug properly thus dumping unburnt fuel into the exhaust and cooked the cat. got so hot a piece broke off inside the cat a few days later and gave the feeling of reduced power at anything over a few thousand rpm broken piece twisted with exhaust flow and blocked the cat!! the joys of owning a car i guess LOL p.s It can be hard to see sometimes on the boot of the lead there will be a tiny little burn mark. Hope this may help.

 

With a ported engine it will flow more air, unless the amount of fuel is increase to match the porting it will run lean and build up more heat. Just another probable cause. That and oil doesn't burn so well in a cat and can clog it up with carbon deposits.