I am having the same problems you are. Haven't been able to update any apps for about 4-5 days it seems. Same error code as well. I'm stock, running 4.1.. Any help on this would be greatly appreciated.
I think when I ran into this problem on one of the ROMs I had I re flashed it and it went away. I did try clearing the data and everything like you have and nothing worked. I unfortunately as jnt said your only option may be a factory reset.
I never tried adding another Gmail account to my device but maybe you can do that and delete the original account? Again I've never attempted this so I don't even know if that's possible
You can remove an account, and then restore it without a factory reset. Add or remove accounts - Android OS Help <-- it is talked about near the bottom there. A coworker buddy of mine had a wacky problem with the playstore, and this solved it for him. I do not recall if it was this specific problem, but I did do this for him and he was able to use the market properly.
Note this doesn't delete anything on your phone, for the few seconds you are logged out of your account you won't be able to use any of the google services though (which should be expected).
A factory reset would probably be my next thing to try.
Thanks for all information and replies. After trying once again just about everything (besides removing my account & reinstalling it) you all have recommended I'm still at a lost. And the few apps I got rid of (most recently downloaded or purchased) are gone for good. I'm afraid to remove my account because it does state that I will lose everything associated with it. Guess it's my only other option other than a factory reset at this point.