I am in the same boat. What I found is that text messages as well as Outlook will continue to run in the backgroud once you have used them. After reading several posts on this board, it appears that this is a bug in the system.
I have the extended battery as well and can sleep for 7 hours and its dead because the programs run in the background. I tried a master reset and now the Outlook has stopped but the text message is still running.
When I first got the phone it was wonderful and the battery lasted days, now with all the programs I put on and going online etc...It was down to a matter of hours before a charge was needed and this was at idle for most of the time. Maybe an hour, if that, of IE browsing.
Annoying but it seems its a known issue.
ROb