iphone boot freeze / recovery to 4.2.1
yesterday, i got my new iphone 4g, then i jailbreaked it and installed a lots of apps. After that i realized that an app that i have installed doesn't run and so it crash each time i tried to start it. As a matter of fact i deleted this app and installed the same one in another version with the result that my iphone 4 needed to restart. In the time while my iphone restart, at the moment the boot logo appears the iphone freeze.
Never the less i can access the recovery mode and dfü mode, but i can't restore it because i need the current firmware version and i didn't saved the shsh bloob or made a backup in itunes. Can somebody please help me with this issue.
I just need to delete the problematic app or a way to restore the iphone to 4.2.1.
The iphone was jailbreaked with greenpoisen and redsnow.
Maybe i can transmit an patch with an exploit and execute it so the app will be deleted.