That's not it. If it was none of us who have had this problem could have gotten it fixed. But that doesn't mean it's not a T Mobile issue.
Do we know if anyone who ISN'T on T Mobile has had this problem? I know a bunch of people have had the issue. Is there anyone who has had this issue who's NOT on T Mobile?
Try this....Delete ALL your APN's. The re input the T Mobile APN from scratch. (Obviously math sure you know what the setting are)
Maybe your APN is corrupted somehow even though all the values are correct.
Have you changed anything on your plan lately? Added minutes? Got a new SIM? Anything where T Mobile has made changes to your account? I spent an hour on the phone with their tech people when I had the problem and the guy told me data issues are often caused by your account getting messed up. They can try a whole bunch of other things on their end like canceling your SIM card and reinstating it to make sure it's properly registered in the system.
The last thing the T Mobile tech told me to do was a full factory reset. Obviously a complete wipe and fresh install accomplishes the same thing. But give that another shot. Do a full wipe, fresh install, and delete the extra APN's then.
Yeah, I tried making a new APN from scratch yesterday, and that didn't help, either. While I was doing it, I also discovered that trying to restore to defaults (I believe it's in the menu when you're looking at the list of APNs; I can't check right now because I'm restoring my nandroid backup) doesn't work, and trying to search for networks also fails.
I haven't changed anything on my plan in about 2 years, when I bought my Samsung Vibrant. That Vibrant still works and gets a data connection with this SIM, and so does this Sensation when I'm on a Sense ROM, which is why I think it's something specifically to do with AOSP ROMs. I'm thinking about digging up my old Sensation (it still works, but is kind of ugly after it hit the sidewalk at high speed in a fit of temper...) and doing some experimentation with it while I go Senseless on my primary phone. I'm going to miss JB, though
EDIT: Oh, now someone's just screwing with me. Guess who has a data connection again? Not going to complain, of course, but jeez....
EDIT2: Thanks again to everybody who tried to help me.
EDIT3: Nevermind. It's blinking again.