Restore the device using a computer with iTunes. When you're going through the setup assistant again, try setting it up as new. Test the device for a bit. If the issue is fixed, great, try putting your backup on it again. If the issue comes back then we know the content on your backup is causing the issues. Hopefully this helps.
I had the EXACT same problems. Here's what I did, and now my phone is fine. I can't say which of the two fixed it though.
1. Clean out connector port - all the dust that you can see. Others have suggested this. This alone did not fix my problems.
2. Let the battery die completely. And I mean all the way. Letting it die until you get the battery with the red bars is not sufficient (I tried this with no success). When you no longer see any response to any button presses, then recharge (or wait a little longer!) .
It could be that step two is all you need to do, but the reason I think both steps are necessary is because I replaced the battery and that did not fix the problem.
I'm very disappointed in Apple for not having a solution to this problem. A trip to the Genius Bar told me to replace the hardware, I was 2 weeks out of warranty and they would not replace it. Hope this helps.
I cleared my connector from dust and dirt and I also let my battery die several times. The battery was completly dead, not even the red bar showed up anymore.
My problem remains unsolved. But I can tell that changing the battery had the effect that my iphone won't go off at 20% anymore but at 2-3%. So far so good. But still, I lose a lot of battery over night while not charging. I turned off every single service apple provides and tested the battery response to turning off different services. But that seems not to be the problem. A lot of people say facebook is very battery hungry. But I couldn't approve this as well.
Dissapointed doesn't even comes close to what I am. Apple wanted 160 € for changing the battery.
Apple, are they mad?...
Well, I don't know if anybody is reading this anymore, but it may help someone who's having the "standby = usage" or phantomusage issue.
As many people suggested in other discussions I resetted my Iphone like a hundred times, turned everything off and even change my carrier. But I always ended up having the extrem battery drain (3-5% per h) and the other above describes issues.
This is what fixed my Iphone 4s (FINALLY) after I even got a water damage from cleaning it with 90% alcohol.
Let someone fix your Dock Connector and you'll be fine if none of the suggested solutions help!!!!!!!
Let me know if this helps!