Maybe a dumb question, but I'm a little confused with my iphone.

Its a JB(redsnow) 3g, on 3.0.1 and its getting a little buggy - apps quitting, sluggish etc. so I thought I should erase and start again. Here's where it gets foggy for me:

If I get hold of a new 3.0.1 IPSW and restore as new iphone (DFU mode or otherwise), thus cleaning out any unwanted bits and bobs, can I then sync with itunes, get my contacts and apps back from an old backup then JB and cydia? Or will syncing with an old backup put everything back on my phone, or is it just the legit apple stuff and contacts etc. that get put back on?

Thanks for any help

restore as new iphone so you get rid of the bugs your having now, then restore the contacts and apps and later JB to get cydia

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I'm not so sure I'd do it in that order... mainly because I've never had much luck with jailbreaking after all of my info is synced to the iPhone - everytime I've tried it that way I get stuck in an endless reboot cycle.

My advice is to jailbreak after the OS is restored and prior to syncing any personal info on the phone. After jailbreaking it sync and activate your iPhone - and do it as a new phone not from a backup, then resync your apps, media, contacts, and other data.

Thanks for the help guys!

go straight to the 3.1 custom firmware. don't see why you can't do this so easily!!!
and restore your iphone as new iphone, put back manually the backup!!!