Is it ok to put the stock ecu back in even though my car is street ported? My pfc is untuned and I want to put the stock ecu back in so I can install my main cat and pass smog. (Not enough money for a tune)

 

That it not logical. The stock ecu is made to run a stock port engine with all stock equipment attached.
It might if all cats, stock injectors, air pump, etc were on the engine and in perfect working order.
Is this the case, or are you expecting a miracle?

You might have better results running E85 and just tuning enough to pass the tests.