Need some help with re-doing my phone

[HappyBunny]

I have an iPhone 3G that is jailbroken/unlocked, so I can use it on T-Mobile. It is currently running iOS 3. I am experiencing some crashes of apps and also the phone has gotten kind of slow. So I think it needs to be restored and have the OS upgraded and re-jailbroken.

I have never jail-broken a phone and I really dont understand all these versions. I do know that iOS 4 is not considered all that great for this particular phone. Where do I get an olderOS? (like 3.2) and what jailbreak should I use for it? This is my only phone and I need it for my job, so I dont want to screw it up!

THanks for any help you can provide!

[iYeow]

I suggest you restore to 3.1.3. Download the 3.1.3 ipsw.
Open up itunes and Shift + restore to 3.1.3 ipsw. Do not hit restore in Itunes.
Read this guide : How to Jailbreak 3.1.3 iPhone 3G & iPod Touch 1G/2G Windows & OS X

[HappyBunny]

Thanks! Will this also unlock the phone again? I ask because there are warnings all over that page that you shouldnt use this if you want to unlock your phone.

[iYeow]

Yes, it will