I Smell gas when idelling

I just changed the motor and tranny in this 2.2L '97. I have checked every line thourougly as well as all conections; there are no leaks. Yet still only when the car is stopped and idelling I smell gas. I am looking for any ideas. Also I want to know if it is nesecary to put the 1psi in that strader valve comming from the purge. The enging did pass an e-test, but I need to find this smell.