Convert Iphone 3.1.3 App to 4.2 SDK to run on simulator

I currently have an application project that is coded for IOS 3.1.3 on XCode 3.1. I need it converted to ios 4.2 with the ability to run it on the Iphone Simulator 4.2 The app when ran on base sdk 4.2 with iPhone Simulator 4.2 it crashes on several screens. I was assured the application runs fine on a device (that I can not test yet) I think the introduction to Sqllite 3.0 lib may be the issue I am not sure - thats what I was told. Please use XCode 3.2 or latest.