popping though passenger side exhuast

[truckdude239]

after fixxing my lean codes with a new pump and filter 65 psi running no more engine light i have a random pop/backfire out the passenger side exhuast, plugs all look good no other running issue pently of power, but random backfire/poping, someone recomened getting the toon checked but im not sure as ive had the ls swap for about 13 year no problems till now any ideas what to check, it has new intake gaskets, and dephli mass flow air sesnor when we where battleing the lean codes