My 4 year old is in a nasty phase now too. It happens to everyone.
It also happens to everyone that what works one day won't work the next. That's just the way it is with a child that is testing the boundaries. If you are perfectly consistent for about, oh, SIX MONTHS STRAIGHT OH MY GOD, then it mellows out and you get about 6 months of peace before it starts over again.
Look. You have made progress. She now understands that you don't get to play unless you help clean up. She reforms, says she will help, then when you return her toys, SHE DOES HELP. Then she backslides. Look, this is normal. This is every child, and to be honest, most adults. Constantly rewarding and punishing, even for the same things over and over, that's just parenting. This part of your life is completely typical. She is not unusual in trying to get out of her chores.
It sounds like what you are having the hardest time dealing with is the smart mouth. You can either ignore it completely or you can fold it into the things she gets punished for. Either way, you have to separate your emotions from your response, as difficult as that is. It sounds to me like you are getting genuinely upset from the hurtful things she is saying, but she's only 3; it's not fair to attribute adult motivations to her. She's trying to get a reaction from you, sure, but she isn't saying things to hurt you, do you see the difference? You simply can't let yourself be genuinely insulted by your 3 year old; you just have to get past that.
Make sleep a priority for you. It's much easier to respond well to a nasty toddler when you are rested. Miss TV. It's worth it. Try this for a week. See if it works.
Then, see what works for you. What if you ignore her completely, and focus only on her actions. Let her grumble about time-outs, picking up toys, whatever. She's only 3; who cares what she grumbles about? Not your problem.
Or, if you can do this calmly, and she isn't grumbling but saying something nasty straight to you, say "you are not allowed to talk to me like that; you can say you're sorry or you can get a time-out (or lose toys for one more day, or whatever)" and give her a chance to say sorry.
I have difficulty sometimes avoiding escalation with my daughter, because she will ALWAYS escalate wtih me. She will NEVER back down, so at some point I have to quit adding on to her punishment and just start it, or stop responding entirely and throw in something completely different. Humor works sometimes. If she says she wants a new mommy, say, OK, can I leave you here and go to the mall by myself for five hours and find you one? Maybe I can get a massage and you can try the new mommy out for a while? Ask her what kind of new mommy she wants. Then say, well, I found one that will do what you wanted, but she's purple and has only one eye, is that ok?
If you can find an activity that works as a "reset button" that puts you both back in a good mood almost all of the time, that's also a good approach. Good luck.