I have an ofna/picco 7 port and have similar problems. And have heard of others with the same kind of problems.
Some of those problems are that the Ofna/piccos are meant for 15% nitro, unless you add some shims under the head.
But My 7 port did over heat the 1st tank. Stock settings too.
my thoughts were to look at the carb for imperfections, and to try another carb that I know works fine.
I have a 3 port Picco 12Rc I modded it and runs like a champ. It'll give up its carb as an experiment.
Otherwise steve @ at ofna will have a pissed off store manager on his hands.
You want me too selll more of those engines-- then make sure they are up to snuff.
You should be able to take an engine out of the box and fire it up without having it go lean on ya.