Help please!!!cannot upgrade after 4.2.1 jailbreak getting 2 errors!!! Help!!!

[needapple101]

I jailbroke my iphone 4 when it was on the 4.2.1 firmware using greenpois0n. I saved my SHSH blobs using Tinyumbrella. I no longer wish to have a jailbroken iphone so I have been trying to restore and upgrade my firmware. If i dont run tinyumbrella I receive the "not eligible" error so I run tinyumbrella and select the 4.2.1 IPSW by holding option on my macbook in itunes and it begins. It does what its supposed to but when it gets to about 75% it gives me the 1013 error. I tried deleting the gs.apple from terminal but it still gives me that error. PLEASE HELP! I would greatly appreciate it!!!