fuelpump relay code and lean fuel code

I have a 96 neon with code 42 and 51. I replaced the fuel pump and it did not help. I can't seem to find a vac. leak. The car runs fine while I excelerate but when you let off the gas it lunges. any ideas???

Sounds like a air leak. Spray the intake and throttle body with a small water bottle and see if the rpm's change.

I tryed spraying all the air lines with water and the idle never changed. Is there a better way to check for air leaks? Thanks