Galaxy Note software version 4.0.3 sucks battery!!

Hi, I owned a Galaxy note with preloaded version 3??? and was working well until there was a prompt recently asking whether I would like to upgrade both the firmware and software which I accepted and now regretted.
After upgrading, I noticed that the Galaxy note is now sucking my battery power!! Even on standby and reading a few sms, the battery level would be severely drained. Each time I ensured that there is no active appliactions on but still the problem existed.
I understood that this version 4.0.3 is having such problem and when checkeed on upgrade to 4.0.4 the reply was "no update" available?
I believed the battery drain is due to the recent softwrae upgrade because before the upgrade, the battery level hardly goes below half level.
Is there anyway to downgrade or upgrade ?
Can sonebody help?
Thanks