97 sunfire problem with antitheft

[kherault]

hi,
I have a problem, i just installed a 2.4 liter in my 1997 sunfire, i had a 2.2 liter in it
before. What i did is i took the 2.4 out off a 1996 sunfire with its computer and wireing
and installed it in my 1997 and since then my car starts but stalls right away. I change
the ignition switch cause the old one didnt work no more. I bought a antitheft lock decoder
called 555L and i dont have a remote starter on the car .What should i do?
Any help whould be greatly appreciated