My phone was jailbroken using a custom ipsw and then i still had to unlock it with ultrasnow even tho i am on ATT. most of my push notification apps are in my folders using categoriesSB and i do not get any of the notifications. Such as from beejive im. and the push notifications are turned on in the settings. any help is appreciated.
You hacktivated your phone, as you should not have. That's why you had to unlock it to get your AT&T SIM to work, and that's why your push notifications don't work. I hope you have your SHSH's on file in Cydia; if so, you can make a new custom firmware with the "activate" checkbox unchecked and use Saurik's solution to shift restore in iTunes. Otherwise, you're kinda out of luck.
Yes, as long as you have your SHSH's stored thru sauriks cydia server. Heres a quick guide http://www.ihackintosh.com/2010/02/downgrade-iphone-3gs-os-3-1-3-to-3-1-2-with-cydia-shsh/ Then you could restore to an unactivated firmware and officially activate in order to have push and everything else function properly. If not itunes wont let you restore to anything but the latest 3.1.3 version thats not jailbroken at the moment for 3GS models.