Yeah it like pops alot on deceleration. Its kinda amplified cuz all i have is a cat and res.

 

Are you still having this problem Ely?

 

Sounds like a leak at the header/manifold gasket at the engine. An air leak will cause a backfire on decel. Also, air being pulled in might show up as running lean.

 

Good one you might have nailed it with the leak comment. He might want to check around the header/manifold gasket area as suggested for leakage and also the manifold to mid-pipe connection. While under there make sure that both O2 sensors are snug as well that will insure everything is sealed tight from the engine to the axle-back point. You could always swap back in the OE manifold to see if that fixes all the issues you are having.