I only noticed the data drop issue recently, but that might be because I'm on wifi the vast majority of the time. Undercover - I'm experiencing basically the same issue as you are, however my data signal seems to reconnect itself after about 15-20 seconds.
Running stock rooted ROM, motley kernel here, UVed quite a bit, though I don't know if that would cause any problems. Will try changing some APN settings tomorrow and see what happens
Stock ROM 4.2.2 Rooted
Motley Kernel b39
CWM Touch Recovery 126.96.36.199