i have a 3gs (old bootrom) at 4.0.1 baseband, 5.13, unlocked and jailbroken, while trying to upgrade to 4.2.1, i created a custom ipsw with a bundle to keep the baseband. i've tried restoring every way, even with pwned dfu, and i either get stuck in preparing iphone for restore or a itunes 1600 error, any help would be appreciated