How to revert iOS4 to 3.1.3 on 3G

[Lukeksk]

I upgraded my jailbroken iPhone 3G on OS 3.1.3 to iOS4. I tried jailbreaking with RedSnow and later Pwnage but both seem to leave my 3G un-jailbroken. No big deal - I could live with an un-jailbroken 3G.

However, what I could not live with was a very slow 3G iPhone and most importantly, an un-usable 3G. Outside of any wifi access, my iPhone could not get any data connection.

So I really want to revert back to OS 3.1.3. Is this possible? If yes, how can I do so?

Many thanks.

 

[Matthew Yohe]

Have you tried running the 3G without restoring from a backup?

 

[pbateman]

Not sure how you can go back...but for whatever its worth I upgraded my old 3G to 4.0 from 3.1 and was able to jailbreak with RedSnow (and unlock with Ultrasnow) without a problem....might wanna give it another shot?
I'm having no issues as far as 3G connections or slow phone

 

[SpaceKitty]

On a 3G you can always go back.

Download the firmware version you want from THIS site. Don't forget where the file downloaded to.

Connect the phone to the computer and let it load up in iTunes. Hold the option key as you click on restore and browse to where you downloaded the file above and click on it. Itunes will be begin restoring to that firmware. It will end with some error such as 1015 but don't worry, you are at the version you restored to, the phone just needs to get kicked out of recovery.

Now download recboot from THIS site. Run it and hit the kick out of recovery button. The phone will boot up and you are now all done.

 

[LAS.mac]

Pretty much what SpaceKitty said.

Here is a good guide to perform the operation http://lifehacker.com/5572003/how-to-downgrade-your-iphone-3g[s]-from-ios-4-to-ios-313

I had to do the same because after upgrade my iPhone 3G to IOS 4, it was pretty much unusable.