Downgrading device to previous OS version

I have an iPhone 3G which I foolishly upgraded to iOS4 to try it out however whenever I try to restore my phone to 3.1.3 via xCode it says that there was an error downgrading the Baseband, and then enters recovery mode requiring me to restore it back to 4 before being able to use it again.

I really need to go back to an earlier version to see if having version 4 on a 3G is causing my slow down problems, is this even possible? [import]uid: 5833 topic_id: 1624 reply_id: 301624[/import]

Eureka, I have done it by following these instructions - http://lifehacker.com/5572003/how-to-downgrade-your-iphone-3g[s]-from-ios-4-to-ios-313 [import]uid: 5833 topic_id: 1624 reply_id: 4713[/import]