I have a 3GS new bootrom running 4.2.1 with greenpoison jailbreak. My phone is starting to play up and i'd like to restore it to 4.2.1 and re jailbreak. i-Tunes will restore to 4.3 and i don't want to as there is no current jailbreak. Can someone please point me in the right direction of how i would restore to 4.2.1 then jailbreak? I have SHSH blobs saved in cydia and on my pc for all 4.? firmware up to 4.3. I have a fairly good understanding of jailbreaking etc, just reading the forum seems a little confusing. Cheers
Run tinyumbrella as a tss server.
Download 4.2.1 fw for your device.
Hit shift alt of pc or option for mac and hold it down and click restore click the firmware you just downloaded and let it do its thing.