Upgrading jailbroken iPhone 4 (CDMA) from iOS 5.0.1 to 6.1.2

Hello good people of iClarified! I am in need of some clarification myself; as stated above, I am seeking to upgrade my Redsn0w jailbroken iPhone 4 on iOS 5.0.1 to iOS 6.1.2. However, my endeavors have not gone so smoothly. Here's what is going on. Background: The whole reason behind me wanting to update my firmware (besides it being well-needed) is primarily because my phone has suffered from a corrupt Cydia file. Cydia will neither function, nor will any of my plugins, mods, or even my large list of Cydia sources show up, though all still function on my device. Being that I am too lazy to try to fix this, I simply manually backed up my iPhone via SSH and prepared for a complete restore. Since updating my iPhone 4 to iOS 5, and being that it is on the Verizon CDMA network, when I tried to jailbreak it, Redsn0w was unable to do so without me using a cracked firmware. I do believe that required Redsn0w to alter the ECID, so all updates have had to be done using downloaded firmware. I have been trying not to update to 6.1.3 as no untethered jailbreak is yet available. Unfortunately, I do love my jailbreak and all it does, so an unjailbroken iPhone drives me up the wall quickly... Equipment & Software Used: Redsn0w 0.9.15b3 evasi0n jailbreak (latest build) TinyUmbrella 4 iPhone 4 (CDMA) 6.1.2 firmware downloaded from here All SHSH blobs saved from iOS 4.0.1-5.1.1 Late 2011 MacBook Pro 15" quad-core i7 non-retina Latest version of iTunes and OSX My Endeavors Thus Far: First, I began by trying to simply update the firmware via iTunes (Option+Restore). I selected the downloaded firmware and shortly received an error for not having it in DFU mode. Noob mistake. So I quickly fixed that, throwing it into Pwned DFU mode via Redsn0w and took another shot at it. Error 16xx. Secondly, I did a little research to find out that it was the host files due to the jailbreak. Going into TinyUmbrella, I disabled all Cydia checkmarks AND edited my host file to clear it of any other addresses besides Apple's. Flushed the DNS cache, ran ping gs.apple.com and it returned with the repeating 127.0.0.1. Beautiful! I switched my firewall off just to be sure that it would cause me no problems as well as initiated TU's TSS Server, then BAM.... Error 1601. Thirdly, after a plethora of Error 1601's, "Device not eligible for build" and no resolution, I decided to give Redsn0w's Restore option a chance (since it can upgrade/downgrade firmwares without iTunes). Praying that this would be my savior, it seemed to run flawlessly....well, until it was waiting for the device to reboot. And, of course, I was hit with another error: Error 2831. I figured this would happen since Redsn0w is not updated to iOS 6. Fourthly, with shoulders slumped and head down, I threw it into DFU mode and hit the restore button, hoping that iTunes would just restore my phone to 6.1.3. I returned a few hours later to find that "An unknown error occurred". Conclusion: I am sure I have not included EVERYTHING I have done; however, hopefully this shall give you a good idea of what has been done. I have tried trouble-shooting the Error 1601, though nothing has worked thus far. I have seen that it could be a result of a bad USB port, although I have tried both to no avail (both USB spots are plugged with either my mouse, flash drive, external HDD or my iPhone cord and have always worked flawlessly, so I doubt they are bad). I have been working on and off on this project for over 2 months now, and have exhausted all resources I have found. Due to working full time and school, I have not the time to screw with it anymore, so ANY help is GREATLY appreciated!