I upgraded to iOS 4 on my 3GS but now I want to downgrade back to 3.1.3 and jailbreak. I saved my SHSH blobs on Cydia. is there a good guide for doing this?? I read quite a bit by Googling but every set of instructions is slightly different and now I'm in brain lock. Any suggestions would be most helpful. Thanks.
Did you check iclarified? I believe there's a good guide there.