Your developer is done for.
C-41 developer is supposed to last six weeks and then die, according to Kodak. Based on personal experience, I wouldn't try to push it past that point, especially since the developer itself is so darned cheap. I've had negs completely ruined, 100% useless because I said, "Oh, it's only two weeks past, it's tightly sealed, and I haven't used it much." So much for a ten pack of 4x5 film ($16 at the time) and the day it took me to shoot it. Portraits too; even worse.
I'd also forget cheesy blix kits and go for the bona fide Kodak C-41 process chemicals. There are many reasons named over and over in the archives. But maybe the one that will make the largest immediate impact is cost. Developer is cheap, and can even be replenished. Bleach lasts for twice as many rolls as the developer does, and then can be regenerated, or it can be constantly replenished, as it has no shelf life. The only thing that makes it go bad is using it, not sitting. C-41 fixer is as cheap as dirt (maybe even cheaper, depending on the quality of the dirt), and also lasts for twice as many rolls as the developer, or can be replenished. Blix starts degrading the second it is mixed, and each chemical ends up not doing its job as well as it should.